Selling, General and Administrative Expenses. Selling, general and administrative expenses increased $5.6 million, or 8.0%, to $74.8 million in the third quarter of 2021 from $69.2 million in the third quarter of 2020. The increase was due primarily to the general impact on expenses of opening 19 new stores since the third quarter of 2020. Also contributing to the increase was a $1.0 million increase in incentive compensation resulting from favorable operating results in relation to budget. As a percentage of sales, selling, general and administrative expenses improved 200 basis points to 32.8% in the third quarter of 2021 from 34.8% in the third quarter of 2020.
Depreciation. Depreciation expense increased $0.8 million, or 17.5%, to $5.5 million in the third quarter of 2021 from $4.7 million in the third quarter of 2020.
Income Tax Expense. Income tax expense was $2.5 million in the third quarter of 2021 compared to $2.2 million in the third quarter of 2020 due primarily to an increase in pretax income.
Net Income. Net income increased $2.0 million to $9.0 million in the third quarter of 2021 compared to $7.0 million in the third quarter of 2020 due to the factors discussed above.
Thirty-Nine Weeks Ended October 30, 2021 and October 31, 2020
Net Sales. Net sales increased $219.2 million, or 41.3%, to $750.6 million in the first thirty-nine weeks of 2021 from $531.4 million in the same period of 2020. The increase in sales was primarily due to the temporary closure of all of our stores in the first half of 2020 as a result of the COVID-19 pandemic, combined with strong comparable store sales and the opening of 19 new stores since the end of the third quarter of 2020, partially offset by the impact of closing four stores and lost sales due to Hurricane Ida.
Cost of Sales (exclusive of depreciation). Cost of sales (exclusive of depreciation) increased $113.1 million, or 34.5%, to $440.4 million in the first thirty-nine weeks of 2021 from $327.3 million in the same period of 2020. Cost of sales as a percentage of sales decreased to 58.7% in the first thirty-nine weeks of 2021 from 61.6% in the same period of 2020 due to an improvement of 340 basis points in the core merchandise margin (initial mark-up, net of markdowns) driven primarily by lower markdowns, along with an improvement of 70 basis points in shrinkage, partially offset by an increase of 120 basis points in freight costs.
Selling, General and Administrative Expenses. Selling, general and administrative expenses increased $47.2 million, or 26.0%, to $228.1 million in the first thirty-nine weeks of 2021 from $180.9 million in the same period of 2020. The increase was due primarily to significant favorable one-time expense reductions in the first half of 2020 related to the COVID-19 pandemic, including furloughs, store closures and reduced operating hours, abated rents and other COVID-19 cost credits. Also contributing to the increase was a $14.0 million increase in incentive compensation resulting from favorable operating results in relation to budget, as well as the general impact on expenses of opening 19 new stores since the third quarter of 2020. As a percentage of sales, selling, general and administrative expenses improved 360 basis points to 30.4% in the first thirty-nine weeks of 2021 from 34.0% in the first thirty-nine weeks of 2020.
Depreciation. Depreciation expense increased $0.6 million, or 4.4%, to $15.2 million in the first thirty-nine weeks of 2021 from $14.6 million in the same period last year.
Asset Impairment. There were no asset impairment charges in the first thirty-nine weeks of 2021. In the first thirty-nine weeks of 2020, impairment charges related to an underperforming store totaled $0.3 million, comprised of $0.2 million for an operating lease right-of-use asset and $0.1 million for leasehold improvements and fixtures and equipment.
Income Tax Expense. Income tax expense was $14.4 million in the first thirty-nine weeks of 2021 compared to $1.8 million in the first thirty-nine weeks of 2020 due primarily to higher pretax income this year.
Net Income. Net income was $52.4 million in the first thirty-nine weeks of 2021 compared to $5.9 million in the same period of 2020 due to the factors discussed above.
Liquidity and Capital Resources
Our principal sources of liquidity consist of: (i) cash and cash equivalents (which equaled $12.0 million as of October 30, 2021); (ii) short-term investment securities (which equaled $35.5 million as of October 30, 2021); (iii) short-term trade credit; (iv) cash generated from operations on an ongoing basis as we sell our merchandise inventory; and (v) a revolving credit facility with a $75 million credit commitment (with no borrowings as of October 30, 2021). Trade credit represents a significant source of financing for inventory purchases and arises from customary payment terms and trade practices with our vendors.