We earned $1.27 per share on revenue of $834 million.
Same-store revenue grew by 9% compared to the third quarter of 2020, as work and bookings are returning as COVID challenges decrease.
Our backlog was over $1.9 billion this quarter, which is a $270 million same-store increase over this time last year.
Our free cash flow continues to be strong, and yesterday we increased our dividend by 8%.
Revenue for the third quarter of 2021 was $834 million, an increase of $120 million or 17% compared to last year; same-store revenue increased by a strong 9%, with the remaining increase resulting from our acquisitions of TEC and Amteck.
Gross profit this quarter was $159 million, a $12 million improvement compared to a year ago while gross profit percentage was 19.1% this quarter compared to 20.6% for the third quarter of 2020.
Our gross profit percentage related to our Mechanical segment was strong at 20.1% and margins in the Electrical segment have increased significantly compared to last year.
SG&A expense for the quarter was $95 million or 11.4% of revenue compared to $91 million or 12.7% of revenue for the third quarter in 2020.
On a same-store basis, SG&A was down approximately $2 million, primarily due to tax consulting fees that we incurred in the prior year.
Our year-to-date 2021 tax rate was in the expected range at 24.1%.
Net income for the third quarter of 2021 was $46 million or $1.27 per share.
This compares to net income for the third quarter of 2020 of $50 million or $1.36 per share, as last year included a $0.17 benefit that resulted when we settled tax audits from past years.
Excluding that discrete item from last year, our earnings per share increased by 7% compared to the record level of a year ago.
For our third quarter, EBITDA was up significantly to $82 million, an increase of 15% over the prior year.
And through nine months, our EBITDA is $188 million.
Free cash flow in the first nine months was $139 million, as compared to $199 million in 2020.
In addition, we will be paying the federal government an extra $16 million of payroll taxes next quarter that were deferred under the CARES Act in 2020.
Since the beginning of the year, we have repurchased 346,000 shares which is almost 1% of our outstanding shares at an average price of $73.69.
Since we began our repurchase program in 2007, we have bought back over 9.6 million shares at an average price of less than $22.
Amteck is reported in our Electrical segment and it is expected to contribute annualized revenues of approximately $175 million to $200 million and earnings before interest taxes, depreciation and amortization of $14 million to $17 million.
Backlog at the end of the third quarter of 2021 was $1.94 billion.
Year-over-year our backlog is up by over $500 million or 36%.
Same-store backlog increased by 19%, a broad base increase.
Industrial customers were 43% of total revenue in the first nine months of 2021.
Institutional markets, which include education healthcare and government are strong and represented 33% of our revenue.
The commercial sector is also doing well but without changing mix it is now a smaller part of our business at about 24% of revenue.
Year-to-date, construction was 77% of our revenue with 46% from construction projects for new buildings and 31% from construction projects in existing buildings.
Service was very strong this quarter and our increasing service revenue was 23% of our year-to-date revenue with service projects providing 9% of revenue and pure service including hourly work providing 14% of revenue.
Year-to-date service revenue was up by 11%.

Summary:
We earned $1.27 per share on revenue of $834 million.
Net income for the third quarter of 2021 was $46 million or $1.27 per share.
Backlog at the end of the third quarter of 2021 was $1.94 billion.