IMPACT OF WORKING CAPITAL MANAGEMENT ON CORPORATE PROFITABILITY OF NIGERIAN MANUFACTURING FIRMS: 2000 TO 2011

CHAPTER ONE: INTRODUCTION

1.1 Background of the Study

Working capital management is a critical aspect of financial management that focuses on the management of a firm’s short-term assets (current assets) and short-term liabilities (current liabilities). The primary objective of working capital management is to ensure that a firm maintains sufficient liquidity to meet its short-term obligations while minimising the cost of holding current assets. The key components of working capital are: (a) cash and marketable securities, (b) accounts receivable (trade debtors), (c) inventory (raw materials, work-in-progress, finished goods), and (d) accounts payable (trade creditors). The management of these components involves decisions about: (a) the level of cash to hold (cash management), (b) credit terms offered to customers and collection policies (receivables management), (c) inventory levels and reorder points (inventory management), and (d) payment terms negotiated with suppliers (payables management) (Brigham and Ehrhardt, 2017; Ross, Westerfield, and Jordan, 2019).

Working capital management is particularly important for manufacturing firms because they have significant investments in inventory (raw materials, work-in-progress, finished goods) and accounts receivable (credit sales to distributors and retailers). Manufacturing firms also have significant accounts payable (credit from suppliers of raw materials and components). Inefficient working capital management can lead to: (a) stock-outs (production stoppages due to lack of raw materials), (b) excess inventory (high carrying costs, risk of obsolescence), (c) slow collection of receivables (cash flow problems, bad debts), (d) delayed payment to suppliers (damaged supplier relationships, loss of discounts), and (e) liquidity crises (inability to meet short-term obligations) (Drury, 2020; Horngren, Sundem, and Stratton, 2018).

The relationship between working capital management and corporate profitability has been extensively studied. The theoretical predictions are that efficient working capital management (shorter cash conversion cycle, lower inventory days, lower receivables days, higher payables days) leads to higher profitability. The cash conversion cycle (CCC) is a comprehensive measure of working capital management efficiency, calculated as:

CCC = Inventory Days + Receivables Days – Payables Days

Where:

• Inventory Days = (Average Inventory ÷ Cost of Goods Sold) × 365
• Receivables Days = (Average Accounts Receivable ÷ Credit Sales) × 365
• Payables Days = (Average Accounts Payable ÷ Cost of Goods Sold) × 365

A shorter CCC indicates that a firm is converting its working capital into cash more quickly, reducing the need for external financing and improving profitability. However, overly aggressive working capital management (very low inventory days, very low receivables days, very high payables days) may lead to stock-outs, lost sales, damaged customer relationships, and strained supplier relationships, ultimately reducing profitability. Therefore, there is an optimal level of working capital that balances liquidity and profitability (Deloof, 2003; Afza and Nazir, 2009).

The period 2000 to 2011 is significant for Nigerian manufacturing firms. This period includes: (a) the early 2000s (post-democracy consolidation), (b) the banking consolidation of 2005 (which affected access to credit), (c) the global financial crisis of 2008-2009 (which affected demand and financing), (d) the post-crisis recovery period (2010-2011). During this period, Nigerian manufacturing firms faced significant challenges: (a) unreliable electricity supply (high generator costs), (b) poor transportation infrastructure (high logistics costs), (c) foreign exchange volatility (affecting imported raw materials), (d) high inflation (rising input costs), (e) competition from imports (cheaper products from China and other countries), (f) high interest rates (15-25% per annum), and (g) multiple taxation. In this challenging environment, efficient working capital management was critical for survival and profitability (CBN, 2012; Adebayo and Oyedokun, 2019).

The Nigerian manufacturing sector during this period included subsectors such as: (a) food and beverage processing (e.g., Nigerian Breweries, Nestle Nigeria, Unilever Nigeria, Cadbury Nigeria, Flour Mills of Nigeria), (b) building materials (e.g., Dangote Cement, Lafarge Africa, Ashaka Cement), (c) chemicals and pharmaceuticals (e.g., May and Baker, Fidson Healthcare, GlaxoSmithKline), (d) plastics and rubber (e.g., First Aluminum, BOC Gases), (e) metal fabrication and engineering, (f) textiles and garments, (g) leather and footwear, (h) wood and furniture, and (i) packaging. These firms had different working capital requirements depending on their production cycles, credit terms, and inventory characteristics (NBS, 2012; MAN, 2011).

The working capital management practices of Nigerian manufacturing firms during this period were influenced by several factors:

Inflation: High inflation (often double-digit) increased the cost of holding inventory (carrying costs) and reduced the real value of payables (benefiting firms that delayed payment). During inflation, firms have incentives to reduce inventory days (hold less inventory) and increase payables days (delay payment to suppliers). However, suppliers may respond by reducing credit terms or increasing prices (Drury, 2020).

Interest Rates: High interest rates (15-25%) increased the cost of financing working capital (bank overdrafts, short-term loans). Firms with high working capital requirements (long inventory days, long receivables days) faced higher financing costs, reducing profitability. Efficient working capital management (reducing CCC) reduced the need for costly external financing.

Foreign Exchange Volatility: Many manufacturing firms imported raw materials (e.g., barley for breweries, chemicals for pharmaceuticals, machinery for manufacturing). Foreign exchange volatility (Naira depreciation) increased the cost of imported raw materials, affecting inventory valuation and payables (if denominated in foreign currency).

Credit Constraints: Following the 2005 banking consolidation and the 2009 banking crisis, access to bank credit became more restricted. Manufacturing firms had to rely more on trade credit (supplier credit) and internal funds (retained earnings). Efficient working capital management (reducing receivables days, increasing payables days) became more important (CBN, 2010).

Competition: Intense competition from imports and other domestic manufacturers put pressure on profit margins. Firms with efficient working capital management (lower inventory days, lower receivables days, higher payables days) had lower costs and could offer competitive prices.

The relationship between working capital management and profitability can be measured using several profitability metrics:

• Return on Assets (ROA) = Net Profit ÷ Total Assets – measures how efficiently a firm uses its assets to generate profit.
• Return on Equity (ROE) = Net Profit ÷ Shareholders’ Equity – measures return on owners’ investment.
• Gross Profit Margin = (Revenue – Cost of Goods Sold) ÷ Revenue – measures profitability after direct production costs.
• Net Profit Margin = Net Profit ÷ Revenue – measures overall profitability after all expenses.
• Operating Profit Margin = Operating Profit ÷ Revenue – measures profitability from core operations (Drury, 2020).

This study focuses on ROA as the primary profitability measure because it is directly affected by working capital management (working capital is a component of total assets). Firms with lower inventory days, lower receivables days, and higher payables days have lower investment in working capital (lower current assets, higher current liabilities), which reduces total assets (denominator of ROA) and increases ROA, assuming net profit remains constant.

Empirical studies on working capital management and profitability in manufacturing firms have been conducted in various countries. Deloof (2003) studied Belgian firms and found a negative relationship between cash conversion cycle and profitability (shorter CCC associated with higher profitability). Afza and Nazir (2009) studied Pakistani firms and found that aggressive working capital management (shorter CCC) was associated with higher profitability. In Nigeria, studies have found mixed results; some found a negative relationship between CCC and profitability, others found no significant relationship (Adebayo and Oyedokun, 2019; Okafor and Udeh, 2020).

The period 2000-2011 provides a unique opportunity to study working capital management in Nigerian manufacturing firms because it includes both pre-crisis and post-crisis periods, as well as a period of significant economic and financial sector reforms. The findings will provide insights for financial managers, investors, and policymakers.

Finally, this study focuses on Nigerian manufacturing firms for the period 2000-2011. By examining the relationship between working capital management components (inventory days, receivables days, payables days, cash conversion cycle) and profitability (ROA), the study can provide insights for financial managers seeking to optimise working capital to enhance profitability. The findings will contribute to the literature on working capital management in developing economies (Yin, 2018; Creswell and Creswell, 2018).

1.2 Statement of Research Problem

Nigerian manufacturing firms during the period 2000-2011 faced significant challenges: (a) high inflation (double-digit rates), (b) high interest rates (15-25%), (c) foreign exchange volatility, (d) unreliable electricity supply (high generator costs), (e) poor transportation infrastructure, (f) competition from imports, (g) credit constraints (especially after the 2009 banking crisis), (h) high production costs, (i) low capacity utilisation (often below 60%), and (j) thin profit margins. In this challenging environment, efficient working capital management (inventory management, receivables management, payables management) was critical for survival and profitability. However, many manufacturing firms struggled with working capital management, leading to:

1. Excess inventory: High inventory levels tied up cash, increased carrying costs (storage, insurance, obsolescence), and reduced profitability. Overstocking of raw materials (due to import delays) and finished goods (due to weak demand) were common.
2. Slow collection of receivables: Long credit terms offered to customers (distributors, retailers) and weak collection efforts led to high accounts receivable days (DSO). This tied up cash, increased bad debts, and required costly external financing.
3. Delayed payment to suppliers: Firms delayed payment to suppliers to conserve cash, but this damaged supplier relationships, led to loss of discounts (e.g., 2/10 net 30), and could result in supply disruptions.
4. Long cash conversion cycle (CCC) : A long CCC (sum of inventory days and receivables days minus payables days) indicated that firms were taking too long to convert working capital into cash, requiring costly external financing and reducing profitability.
5. Lack of working capital optimisation: Many firms did not have formal working capital policies or targets (e.g., target inventory days, target receivables days, target payables days). Working capital decisions were made on an ad-hoc basis, leading to inefficiencies.
6. Impact of external shocks: The global financial crisis (2008-2009) reduced demand for manufactured goods, increased customer defaults (bad debts), and tightened credit availability. Firms with poor working capital management were more vulnerable to the crisis.
7. Limited empirical research in Nigeria: While working capital management has been extensively studied in developed countries, there is limited empirical research on Nigerian manufacturing firms, particularly for the period 2000-2011. The relationship between working capital components (inventory days, receivables days, payables days, CCC) and profitability (ROA) is not well understood for Nigerian manufacturing firms.
8. Inconsistent findings in prior studies: Prior studies in Nigeria have produced mixed results (positive, negative, or no relationship). This may be due to differences in sample period, sample composition, measurement of variables, or econometric methods.
9. Lack of sector-specific analysis: Different manufacturing subsectors (food and beverage, building materials, chemicals, textiles) have different working capital requirements (e.g., food products have shorter shelf lives, requiring lower inventory days). Prior studies often aggregate all manufacturing firms, masking sector-specific effects.
10. Policy implications: The Central Bank of Nigeria and the Federal Ministry of Industry, Trade and Investment need evidence on the working capital challenges facing manufacturing firms to design appropriate policies (e.g., credit guarantee schemes, interest rate subsidies, trade finance facilities).

This study addresses these problems by empirically investigating the impact of working capital management (inventory days, receivables days, payables days, cash conversion cycle) on the profitability (ROA) of Nigerian manufacturing firms for the period 2000-2011.

1.3 Objectives of the Study

The specific objectives of this study are:

1. To examine the working capital management practices (inventory days, receivables days, payables days, cash conversion cycle) of Nigerian manufacturing firms for the period 2000-2011.
2. To assess the profitability (Return on Assets – ROA) of Nigerian manufacturing firms for the period 2000-2011.
3. To determine the relationship between inventory days (average time raw materials and finished goods are held) and the profitability (ROA) of Nigerian manufacturing firms.
4. To determine the relationship between receivables days (average time to collect payment from customers) and the profitability (ROA) of Nigerian manufacturing firms.
5. To determine the relationship between payables days (average time to pay suppliers) and the profitability (ROA) of Nigerian manufacturing firms.
6. To determine the relationship between the cash conversion cycle (CCC) and the profitability (ROA) of Nigerian manufacturing firms.
7. To identify the optimal levels of working capital components (inventory days, receivables days, payables days, CCC) that maximise profitability for Nigerian manufacturing firms.

1.4 Research Questions

The following research questions guide this study:

1. What are the working capital management practices (inventory days, receivables days, payables days, cash conversion cycle) of Nigerian manufacturing firms for the period 2000-2011?
2. What is the profitability (Return on Assets – ROA) of Nigerian manufacturing firms for the period 2000-2011?
3. What is the relationship between inventory days and the profitability (ROA) of Nigerian manufacturing firms?
4. What is the relationship between receivables days and the profitability (ROA) of Nigerian manufacturing firms?
5. What is the relationship between payables days and the profitability (ROA) of Nigerian manufacturing firms?
6. What is the relationship between the cash conversion cycle (CCC) and the profitability (ROA) of Nigerian manufacturing firms?
7. What are the optimal levels of working capital components (inventory days, receivables days, payables days, CCC) that maximise profitability?

1.5 Research Hypotheses

The following hypotheses are formulated in null (H₀) and alternative (H₁) forms:

Hypothesis One (Inventory Days)

• H₀: Inventory days have no significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.
• H₁: Inventory days have a significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.

Hypothesis Two (Receivables Days)

• H₀: Receivables days have no significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.
• H₁: Receivables days have a significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.

Hypothesis Three (Payables Days)

• H₀: Payables days have no significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.
• H₁: Payables days have a significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.

Hypothesis Four (Cash Conversion Cycle)

• H₀: The cash conversion cycle (CCC) has no significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.
• H₁: The cash conversion cycle (CCC) has a significant effect on the Return on Assets (ROA) of Nigerian manufacturing firms.

1.6 Scope of the Study

This study focuses on the impact of working capital management on corporate profitability of Nigerian manufacturing firms for the period 2000 to 2011. The scope is limited to:

Geographical Scope: Nigeria, with a focus on manufacturing firms listed on the Nigerian Exchange Limited (NGX) (formerly Nigerian Stock Exchange) and other significant manufacturing firms with available financial data.

Entities: Manufacturing firms across subsectors: (a) food and beverage processing, (b) building materials (cement, tiles, roofing sheets), (c) chemicals and pharmaceuticals, (d) plastics and rubber, (e) metal fabrication and engineering, (f) textiles and garments, (g) leather and footwear, (h) wood and furniture, and (i) packaging. The sample includes firms that have published annual reports (financial statements) for the period 2000-2011.

Time Period: 2000 to 2011 (12 years). This period was chosen because: (a) it includes pre-banking consolidation (2000-2004), consolidation period (2005), pre-crisis period (2006-2007), global financial crisis (2008-2009), and post-crisis recovery (2010-2011), (b) data availability for manufacturing firms is more consistent for this period, and (c) the period allows analysis of working capital management under different economic conditions.

Working Capital Variables:

• Inventory Days (INVD) = (Average Inventory ÷ Cost of Goods Sold) × 365
• Receivables Days (RECD) = (Average Accounts Receivable ÷ Credit Sales) × 365
• Payables Days (PAYD) = (Average Accounts Payable ÷ Cost of Goods Sold) × 365
• Cash Conversion Cycle (CCC) = INVD + RECD – PAYD

Profitability Variables:

• Return on Assets (ROA) = Net Profit ÷ Total Assets (primary dependent variable)
• Return on Equity (ROE) = Net Profit ÷ Shareholders’ Equity (secondary)
• Gross Profit Margin = (Revenue – Cost of Goods Sold) ÷ Revenue (secondary)

Control Variables:

• Firm Size (log of total assets)
• Leverage (Total Debt ÷ Total Assets)
• Sales Growth (annual growth in revenue)
• Firm Age (years since incorporation)

Data Sources:

• Annual reports and financial statements of manufacturing firms
• Nigerian Exchange Limited (NGX) factbooks
• Central Bank of Nigeria (CBN) statistical bulletins
• National Bureau of Statistics (NBS) publications
• Manufacturers Association of Nigeria (MAN) reports

1.7 Significance of the Study

This study is significant for several stakeholders:

Manufacturing Firms (Management and Financial Managers) : The findings will help financial managers understand the relationship between working capital components (inventory days, receivables days, payables days, CCC) and profitability. Managers can: (a) set target levels for inventory days (balancing stock-out risk vs. carrying cost), (b) optimise credit terms for customers (balancing sales growth vs. bad debt risk), (c) negotiate payment terms with suppliers (balancing cash conservation vs. supplier relationships), and (d) reduce the cash conversion cycle to free up cash and reduce financing costs.

Investors and Financial Analysts: The findings will help investors assess the working capital efficiency of manufacturing firms as part of their investment analysis. Firms with efficient working capital management (low CCC, low inventory days, low receivables days, high payables days) are more profitable and less risky, making them attractive investments.

Creditors (Banks and Trade Creditors) : The findings will help creditors assess the liquidity and credit risk of manufacturing firms. Firms with efficient working capital management have lower risk of default (they generate cash quickly) and are more creditworthy. Creditors may offer better terms (lower interest rates, higher credit limits) to firms with efficient working capital management.

The Central Bank of Nigeria (CBN) : The findings will inform CBN policies on: (a) interest rates (working capital loans), (b) credit guarantee schemes for manufacturing firms, (c) trade finance facilities, and (d) export financing. CBN can also design programs to support manufacturing firms in improving working capital management (training, advisory services).

The Federal Ministry of Industry, Trade and Investment: The findings will inform industrial policy, including: (a) support for manufacturing firms to adopt best practices in inventory management, (b) credit reporting systems to reduce information asymmetry, (c) supply chain finance programs, and (d) infrastructure investment (electricity, roads) to reduce working capital needs.

Academics and Researchers: The study contributes to the literature on working capital management in developing economies, particularly in Nigeria. The study provides empirical evidence on the relationship between working capital components and profitability, which can be used for further research (e.g., comparative studies with other countries, sector-specific studies).

The Manufacturers Association of Nigeria (MAN) : The findings will help MAN design training programs, advocacy, and advisory services for member firms on working capital management best practices.

The Nigerian Economy: Improved working capital management in manufacturing firms will lead to: (a) higher profitability, (b) increased investment in capacity expansion, (c) job creation, (d) reduced reliance on costly external financing, (e) increased tax revenue, (f) import substitution (reduced imports of manufactured goods), and (g) economic growth.

1.8 Limitations of the Study

This study acknowledges several limitations:

1. Data Availability: Financial data for some manufacturing firms may be incomplete or unavailable for the entire period 2000-2011. Some firms were delisted, merged, or did not publish annual reports for some years. The study will use an unbalanced panel to maximise sample size.
2. Self-Selection Bias: Listed firms (which are required to publish annual reports) may have better working capital management practices than unlisted firms. Findings may not be generalizable to unlisted manufacturing firms.
3. Measurement of Variables: The study uses accounting-based measures of working capital (inventory days, receivables days, payables days) that may be affected by accounting policies (e.g., FIFO vs. weighted average for inventory, revenue recognition policies). Differences in accounting policies may affect comparability across firms.
4. Endogeneity: Working capital management and profitability may be jointly determined (reverse causality). More profitable firms may invest in better inventory management systems (causality from profitability to working capital). The study will use panel data methods (fixed effects, instrumental variables) to address endogeneity, but perfect identification is challenging.
5. Omitted Variable Bias: Unobserved factors (e.g., management quality, corporate culture, technology, brand reputation) may affect both working capital management and profitability. The study will include control variables (firm size, leverage, sales growth, firm age) to reduce omitted variable bias, but some factors may remain unobserved.
6. Time Period: The period 2000-2011 includes the global financial crisis (2008-2009), which may have affected working capital management and profitability. The study includes year dummies to control for crisis effects, but the interaction between working capital and the crisis may not be fully captured.
7. Industry Heterogeneity: Different manufacturing subsectors have different working capital requirements. The study will include sector dummies to control for industry effects, but the sample size may not allow for separate analysis of each subsector.
8. Generalizability: Findings may not be generalizable to other time periods (post-2011) or to other countries with different economic conditions, financial systems, and business environments.
9. Cash Conversion Cycle Calculation: The calculation of CCC requires assumptions about credit sales (if not disclosed) and cost of goods sold. Some firms may not disclose credit sales separately; total sales may be used as a proxy, introducing measurement error.

Despite these limitations, the study aims to provide robust, meaningful insights into the impact of working capital management on corporate profitability of Nigerian manufacturing firms for the period 2000-2011.

1.9 Operational Definition of Terms

Working Capital: The difference between a firm’s current assets and current liabilities. It represents the funds available for day-to-day operations.

Working Capital Management: The management of current assets (cash, accounts receivable, inventory) and current liabilities (accounts payable, short-term debt) to ensure that a firm has sufficient liquidity to meet its short-term obligations while minimising the cost of holding current assets.

Inventory Days (INVD) : The average number of days that raw materials, work-in-progress, and finished goods are held in inventory before being sold. Calculated as: (Average Inventory ÷ Cost of Goods Sold) × 365. Lower inventory days indicate more efficient inventory management (faster turnover).

Receivables Days (RECD) : The average number of days that customers take to pay for goods sold on credit. Calculated as: (Average Accounts Receivable ÷ Credit Sales) × 365. Lower receivables days indicate more efficient collection (faster payment).

Payables Days (PAYD) : The average number of days that a firm takes to pay its suppliers. Calculated as: (Average Accounts Payable ÷ Cost of Goods Sold) × 365. Higher payables days indicate that the firm is taking longer to pay suppliers (conserving cash).

Cash Conversion Cycle (CCC) : The average number of days between the payment of cash for raw materials and the collection of cash from customers. Calculated as: INVD + RECD – PAYD. A shorter CCC indicates that a firm is converting its working capital into cash more quickly.

Profitability: The ability of a firm to generate earnings relative to its revenue, assets, or equity. Measured by Return on Assets (ROA), Return on Equity (ROE), and profit margins.

Return on Assets (ROA) : Net profit divided by total assets. Measures how efficiently a firm uses its assets to generate profit. This is the primary dependent variable in this study.

Return on Equity (ROE) : Net profit divided by shareholders’ equity. Measures the return earned on owners’ investment.

Gross Profit Margin: (Revenue – Cost of Goods Sold) ÷ Revenue. Measures profitability after direct production costs.

Operating Profit Margin: Operating profit (earnings before interest and taxes) ÷ Revenue. Measures profitability from core operations.

Net Profit Margin: Net profit ÷ Revenue. Measures overall profitability after all expenses (including interest and taxes).

Manufacturing Firm: A business entity engaged in the physical or chemical transformation of materials, substances, or components into finished products (goods) for sale.

Listed Firm: A company whose shares are traded on the Nigerian Exchange Limited (NGX) (formerly Nigerian Stock Exchange).

Average Inventory: (Beginning Inventory + Ending Inventory) ÷ 2. Used to calculate inventory days.

Average Accounts Receivable: (Beginning Accounts Receivable + Ending Accounts Receivable) ÷ 2. Used to calculate receivables days.

Average Accounts Payable: (Beginning Accounts Payable + Ending Accounts Payable) ÷ 2. Used to calculate payables days.

Cost of Goods Sold (COGS) : The direct costs attributable to the production of goods sold, including raw materials, direct labour, and manufacturing overhead.

Credit Sales: Sales made on credit (not cash). Used to calculate receivables days. If credit sales are not disclosed, total sales may be used as a proxy.

Firm Size: The logarithm (log) of total assets. Used as a control variable in regression models.

Leverage: The ratio of total debt to total assets (Total Debt ÷ Total Assets). Used as a control variable.

Sales Growth: The annual percentage change in revenue. Calculated as (Revenueₜ – Revenueₜ₋₁) ÷ Revenueₜ₋₁. Used as a control variable.

Firm Age: The number of years since the firm was incorporated. Used as a control variable.

Panel Data: A dataset that tracks the same firms (cross-sectional units) over multiple time periods (years). Panel data allows control for firm-specific heterogeneity and is used in regression analysis.

Fixed Effects Model: A panel data regression model that controls for time-invariant firm-specific characteristics (e.g., corporate culture, management quality) by allowing each firm to have its own intercept.

Random Effects Model: A panel data regression model that assumes firm-specific effects are uncorrelated with the independent variables and treats them as random.

Hausman Test: A statistical test used to choose between fixed effects and random effects models.

REFERENCES

Adebayo, K. and Oyedokun, G. (2019). Working capital management and profitability of Nigerian manufacturing firms. Nigerian Journal of Management Accounting, 11(2), 45-68.

Afza, T. and Nazir, M. S. (2009). Impact of aggressive working capital management policy on firms’ profitability. IUP Journal of Applied Finance, 15(8), 20-30.

Brigham, E. F. and Ehrhardt, M. C. (2017). Financial management: Theory and practice (15th ed.). Cengage Learning.

CBN. (2010). Banking supervision annual report 2009. Central Bank of Nigeria.

CBN. (2012). Statistical bulletin 2011. Central Bank of Nigeria.

Creswell, J. W. and Creswell, J. D. (2018). Research design: Qualitative, quantitative, and mixed methods approaches (5th ed.). Sage Publications.

Deloof, M. (2003). Does working capital management affect profitability of Belgian firms? Journal of Business Finance and Accounting, 30(3-4), 573-588.

Drury, C. (2020). Management and cost accounting (11th ed.). Cengage Learning.

Horngren, C. T., Sundem, G. L., and Stratton, W. O. (2018). Introduction to management accounting (17th ed.). Pearson Education.

MAN. (2011). Annual report 2010. Manufacturers Association of Nigeria.

NBS. (2012). Annual abstract of statistics 2011. National Bureau of Statistics.

Okafor, E. and Udeh, S. (2020). Cash conversion cycle and profitability of Nigerian manufacturing firms. African Journal of Business and Management, 7(3), 44-62.

Ross, S. A., Westerfield, R. W., and Jordan, B. D. (2019). Fundamentals of corporate finance (13th ed.). McGraw-Hill.

Yin, R. K. (2018). Case study research and applications: Design and methods (6th ed.). Sage Publications.

CHAPTER TWO: REVIEW OF RELATED LITERATURE

2.1 Introduction

This chapter reviews the literature relevant to the impact of working capital management on corporate profitability of Nigerian manufacturing firms. The review covers the conceptual framework, including current assets, non-current assets, current liabilities, difficulties in managing working capital, and overtrading. The chapter provides the theoretical and conceptual foundation for understanding how working capital management affects the profitability of manufacturing firms.

2.2 Conceptual Framework

A conceptual framework is a structural representation of the key concepts or variables in a study and the hypothesized relationships among them. In this study, the conceptual framework is built around two primary constructs: Working Capital Management (the independent variable) and Corporate Profitability (the dependent variable). The framework posits that working capital management components (inventory days, receivables days, payables days, cash conversion cycle) affect profitability (Return on Assets – ROA). The framework also identifies moderating variables (firm size, leverage, sales growth, firm age, industry) that influence the relationship (Miles, Huberman, and Saldaña, 2020).

2.2.1 Current Assets

Current assets are assets that are expected to be converted into cash, sold, or consumed within one year (or one operating cycle, whichever is longer). The key components of current assets are:

Cash and Cash Equivalents: Cash on hand, cash in bank accounts, and highly liquid investments (treasury bills, commercial paper, money market funds) that can be converted to cash within 90 days. Cash is the most liquid asset but earns little or no return. Holding excess cash reduces profitability (opportunity cost), while holding insufficient cash risks liquidity crises. Cash management involves determining the optimal cash balance (Baumol model, Miller-Orr model) (Brigham and Ehrhardt, 2017).

Accounts Receivable (Trade Debtors) : Amounts owed by customers for goods sold on credit. Accounts receivable arise from credit sales. While offering credit stimulates sales (increases revenue), it also ties up cash (increases working capital requirement), creates the risk of bad debts (non-payment), and incurs collection costs. Credit management involves setting credit terms (e.g., 2/10 net 30), assessing customer creditworthiness, and collecting overdue accounts (Ross, Westerfield, and Jordan, 2019).

Inventory (Stock) : Raw materials, work-in-progress, and finished goods held for production or sale. Inventory management involves balancing stock-out risk (lost sales, production stoppages) against carrying costs (storage, insurance, obsolescence, capital tied up). Inventory models (Economic Order Quantity – EOQ, Just-in-Time – JIT) help determine optimal order quantities and reorder points (Drury, 2020).

Prepaid Expenses: Expenses paid in advance (e.g., insurance premiums, rent, subscriptions). Prepaid expenses are current assets because they will be consumed within one year.

Marketable Securities: Short-term investments (treasury bills, commercial paper, bonds) that can be sold quickly for cash. Marketable securities earn higher returns than cash but are less liquid. Firms hold marketable securities to earn returns on excess cash.

2.2.2 Non-Current Assets

Non-current assets (also called fixed assets or long-term assets) are assets that are expected to provide economic benefits for more than one year. They include:

Property, Plant, and Equipment (PPandE) : Land, buildings, machinery, equipment, vehicles, furniture, and fixtures. PPandE are used in production and operations. They are depreciated over their useful lives (except land). PPandE are not part of working capital but are relevant for profitability (ROA includes total assets, which includes PPandE). Working capital management interacts with PPandE through the cash conversion cycle and financing decisions (Horngren, Sundem, and Stratton, 2018).

Intangible Assets: Patents, copyrights, trademarks, goodwill, software. Intangible assets lack physical substance but provide long-term benefits. They are amortised over their useful lives.

Long-Term Investments: Investments in other companies (equity or debt) held for more than one year.

Deferred Tax Assets: Future tax benefits due to temporary differences between accounting and tax treatment.

Non-current assets are not directly managed as part of working capital, but the level of non-current assets affects the denominator of ROA (total assets = current assets + non-current assets). Firms with high non-current assets (capital-intensive manufacturing) have different working capital requirements than firms with low non-current assets (labour-intensive manufacturing).

2.2.3 Current Liabilities

Current liabilities are obligations that are expected to be settled within one year (or one operating cycle). The key components of current liabilities are:

Accounts Payable (Trade Creditors) : Amounts owed to suppliers for goods and services purchased on credit. Accounts payable are a source of short-term financing (trade credit). Delaying payment to suppliers (increasing payables days) conserves cash but may damage supplier relationships, lead to loss of discounts (e.g., 2/10 net 30), and risk supply disruptions (Deloof, 2003).

Short-Term Debt (Bank Overdrafts, Commercial Paper) : Borrowings from banks or other lenders with maturity less than one year. Short-term debt is used to finance working capital needs (inventory, receivables). High interest rates on short-term debt reduce profitability. Firms with efficient working capital management (low CCC) require less short-term debt.

Accrued Expenses: Expenses incurred but not yet paid (e.g., wages payable, utilities payable, interest payable, taxes payable). Accrued expenses are a source of spontaneous financing (they arise automatically from operations).

Current Portion of Long-Term Debt: The portion of long-term debt (e.g., bank loans, bonds) that is due within one year.

Dividends Payable: Dividends declared but not yet paid to shareholders.

Effective working capital management aims to minimise current assets (especially cash, receivables, inventory) and maximise current liabilities (especially payables) to reduce the cash conversion cycle and improve profitability. However, aggressive working capital management (very low inventory, very low receivables, very high payables) may increase risk (stock-outs, lost sales, damaged supplier relationships). The optimal level balances profitability and risk (Afza and Nazir, 2009).

2.2.4 Difficulties in Managing Working Capital

Managing working capital presents several difficulties for manufacturing firms:

Uncertainty of Cash Flows: Cash inflows from customers are uncertain (customers may delay payment or default). Cash outflows to suppliers, employees, and creditors are more predictable. This mismatch creates the need for cash buffers (reserves) or access to short-term credit.

Seasonality: Many manufacturing firms experience seasonal demand (e.g., food and beverage products have higher demand during holidays, building materials have higher demand during dry season). Working capital requirements increase during peak seasons (higher inventory, higher receivables) and decrease during off-seasons. Firms must finance seasonal peaks (e.g., through bank overdrafts) (Drury, 2020).

Production Lead Times: Firms with long production cycles (e.g., heavy machinery, pharmaceuticals) have higher work-in-progress inventory, longer inventory days, and higher working capital requirements. Reducing production lead times through lean manufacturing reduces working capital.

Supply Chain Disruptions: Delays in raw material delivery (due to supplier issues, transportation problems, port delays) force firms to hold safety stock (buffer inventory), increasing inventory days and working capital. Reliable supply chains reduce working capital requirements.

Customer Credit Risk: Offering credit to customers increases sales but also increases the risk of bad debts (non-payment). Assessing customer creditworthiness is difficult, especially in developing economies with weak credit bureaus. Firms may use credit insurance or factoring to reduce credit risk (Ross et al., 2019).

Supplier Credit Terms: Suppliers may offer limited credit (short payables days) or require advance payment (cash in advance), increasing working capital requirements. Negotiating longer credit terms (e.g., 60 days instead of 30 days) reduces working capital.

Inflation: High inflation erodes the real value of cash and receivables (purchasing power loss) but also erodes the real value of payables (benefiting firms that delay payment). During inflation, firms reduce inventory days (hold less inventory) and increase payables days (delay payment). However, suppliers may respond by reducing credit terms or increasing prices (Okafor and Udeh, 2020).

Interest Rates: High interest rates increase the cost of financing working capital (bank overdrafts, short-term loans). Firms with high working capital requirements face higher financing costs, reducing profitability. Efficient working capital management (reducing CCC) reduces the need for costly external financing.

Currency Fluctuations: For firms that import raw materials or export finished goods, foreign exchange volatility affects the value of payables (if denominated in foreign currency) and receivables (if denominated in foreign currency). Hedging (forward contracts, options) can reduce currency risk but adds cost (Adebayo and Oyedokun, 2019).

Lack of Access to Credit: Many manufacturing firms, especially small and medium enterprises (SMEs), lack access to bank credit (due to collateral requirements, information asymmetry, high interest rates). These firms must rely on trade credit (supplier credit) and internal funds (retained earnings), limiting their ability to finance working capital needs.

Poor Record-Keeping: Many manufacturing firms (especially SMEs) do not maintain accurate records of inventory, receivables, and payables. Without accurate records, they cannot calculate inventory days, receivables days, or payables days, making working capital management difficult.

2.2.5 Overtrading

Overtrading (also called under-capitalisation) occurs when a firm expands its sales (revenue) faster than its working capital base, leading to liquidity crises. Overtrading is common in rapidly growing manufacturing firms that finance growth with trade credit (payables) rather than equity or long-term debt. Symptoms of overtrading include:

Rapidly growing sales: Sales growth exceeds the growth of working capital (current assets minus current liabilities). The firm is stretching its resources too thin.

Declining liquidity ratios: Current ratio (current assets ÷ current liabilities) and quick ratio ((current assets – inventory) ÷ current liabilities) fall below industry benchmarks. The firm may struggle to meet short-term obligations.

Increasing inventory days: The firm holds more inventory (relative to sales) to support growth, but inventory turns slower (higher inventory days). This ties up cash.

Increasing receivables days: The firm offers longer credit terms to customers to stimulate sales, but customers take longer to pay (higher receivables days). This ties up cash.

Decreasing payables days: Suppliers, concerned about the firm’s liquidity, demand shorter credit terms (lower payables days). The firm must pay suppliers faster, reducing cash available.

Negative cash conversion cycle (CCC) : If CCC becomes negative (inventory days + receivables days < payables days), the firm is effectively using supplier credit to finance growth. While negative CCC is efficient, if payables days increase beyond sustainable levels, suppliers may cut off credit.

Bank overdraft utilisation: The firm relies heavily on bank overdrafts (short-term debt) to finance working capital. As overdraft limits are reached, the firm may be unable to access additional credit.

Late payment to suppliers: The firm delays payment to suppliers beyond agreed terms, damaging supplier relationships and risking supply disruptions.

Inability to take discounts: The firm cannot take advantage of early payment discounts (e.g., 2/10 net 30) because of cash shortages, increasing costs.

Increased bad debts: In the rush to grow sales, the firm extends credit to high-risk customers, leading to higher bad debts (Deloof, 2003).

Overtrading can lead to business failure if not addressed. Solutions include: (a) injecting equity (new share capital) to increase the working capital base, (b) obtaining long-term debt (instead of short-term debt) to finance growth, (c) reducing sales growth (slowing down), (d) improving inventory management (reducing inventory days), (e) improving receivables management (reducing receivables days), (f) negotiating longer payment terms with suppliers (increasing payables days), and (g) factoring receivables (selling receivables to a factor for immediate cash). Manufacturing firms in Nigeria that experienced rapid growth after the 2005 banking consolidation were at risk of overtrading (Adebayo and Oyedokun, 2019).

The relationship between working capital management and profitability is non-linear (inverted U-shaped). At low levels of working capital (very low inventory days, very low receivables days, very high payables days), the firm is at risk of stock-outs, lost sales, damaged customer relationships, and strained supplier relationships, reducing profitability. At high levels of working capital (very high inventory days, very high receivables days, very low payables days), the firm has excess cash tied up in working capital, incurring high carrying costs and financing costs, reducing profitability. The optimal level (where profitability is maximised) is somewhere in between (Afza and Nazir, 2009).

Empirical studies have found that the optimal cash conversion cycle varies by industry. For manufacturing firms, optimal CCC is typically between 30 and 60 days. Firms with CCC below 30 days may be overtrading (risk of stock-outs, lost sales). Firms with CCC above 60 days have excess working capital (inefficiency). Nigerian manufacturing firms during 2000-2011 had average CCC ranging from 60 to 120 days, indicating significant room for improvement (Okafor and Udeh, 2020).

The conceptual framework for this study posits that:

• Inventory days (INVD) have an inverted U-shaped relationship with profitability (ROA). Very low INVD risks stock-outs; very high INVD incurs carrying costs.
• Receivables days (RECD) have an inverted U-shaped relationship with profitability. Very low RECD may reduce sales (if credit terms are too strict); very high RECD increases bad debts and financing costs.
• Payables days (PAYD) have a positive relationship with profitability up to a point (delaying payment conserves cash), but excessively high PAYD damages supplier relationships.
• Cash conversion cycle (CCC) has an inverted U-shaped relationship with profitability. Very low CCC (negative) may indicate overtrading; very high CCC indicates inefficiency.