| ● | Strong organic growth, which allowed us to leverage fixed costs. |
| ● | The sequential rise in lumber prices in the second and third quarters, which favorably impacted our gross profit per unit of products sold on a variable price such as ProWood pressure-treated lumber. |
Selling, general and administrative (“SG&A”) expenses increased by approximately $22.5 million, or 25.5%, in the first nine months of 2020 compared to the same period of 2019, while we reported a 22% increase in unit sales. Acquired operations since the third quarter of 2019 contributed approximately $1.9 million to this increase. Accrued bonus expense increased approximately $14.9 million and totaled approximately $26.9 for the first nine months of 2020. The remaining increase was due to increases in salaries and wages and in-store merchandising costs, offset by a decline in advertising and travel and related costs.
Earnings from operations for the Retail reportable segment increased in the first nine months of 2020 compared to 2019 by $74.5 million, or 156.5%, well in excess of our 22% increase in unit sales as a result of the factors mentioned above.
Industrial Segment
Net sales in the third quarter of 2020 increased 4% compared to the same period of 2019, due to a 6% increase in selling prices attributable to the Lumber Market, offset by a 2% decrease in unit sales due to the impact of the pandemic and government imposed shutdowns.
Gross profits increased by 1.8% to $48.2 million for the third quarter of 2020 compared to the same period of 2019. We estimate the higher level of lumber prices (see “Impact of the Lumber Market on Our Operating Results”) caused a decline in margin of 100 basis points as our gross margins dropped to 17.1% from 17.4% last year. We experienced a 70 basis point improvement in our profitability due to the impact of favorable changes in product mix and effectively passing along increases in commodity lumber costs to our customers.
Selling, general and administrative (“SG&A”) expenses decreased by approximately $.4 million, or 1.7%, in the third quarter of 2020 compared to the same period of 2019. Acquired operations since the third quarter of 2019 contributed approximately $0.9 million to our costs. Accrued bonus expense, which varies with our pre-bonus operating profit and return on investment, decreased approximately $.9 million, and totaled $6.1 million for the quarter. The remaining decrease was due to a variety of factors.
Earnings from operations for the Industrial reportable segment increased in the third quarter of 2020 compared to 2019 by $1.3 million, or 6.1%, due to the factors discussed above.
Net sales in the first nine months of 2020 decreased 9% compared to the same period of 2019, due to a 10% decrease in unit sales, reflective of the impact of the pandemic on our Industrial business.
Gross profits in the first nine months of 2020 declined 5.7% to $127.6 million compared to the same period of 2019, while gross margins increased to 16.7% compared to 16.1% for the same period of 2019. We estimate the higher level of lumber prices caused a decline in margin of 20 basis points. The improvement in our gross margin was primarily due to the impact of effective inventory positioning resulting in lower lumber costs early in the year, favorable changes in product mix, and effectively passing along increases in commodity lumber costs to our customers.
Selling, general and administrative (“SG&A”) expenses decreased by approximately $1.4 million, or 1.9%, in the first nine months of 2020 compared to the same period of 2019. Acquired operations since the third quarter of 2019 contributed approximately $2.0 million to total SG&A expenses. Accrued bonus expense decreased approximately $4.2 million compared to the same period of 2019 and totaled approximately $12.5 for the first nine months of 2020. This reduction was partially offset by increases in salaries and wages, sales compensation, and amortization expense.