Second quarter of 2021, revenues increased to $188.8 million compared to $89.3 million in the second quarter of the prior year.
Operating loss for the second quarter was $1.2 million compared to an adjusted operating loss of $35.9 million in the second quarter of the prior year.
EBITDA for the second quarter of this year was $17.3 million compared to adjusted EBITDA of negative $17.8 million in the same period of the prior year.
We approached breakeven per share results in the second quarter of 2021 compared to an adjusted loss per share of $0.10 in the second quarter of 2020.
Cost of revenues during the second quarter of 2021 was $145.8 million or 77.2% of revenues compared to $80 million or 89.6% of revenues during the second quarter of the prior year.
Selling, general and administrative expenses increased to $29.4 million in the second quarter of this year compared to $28.8 million in the second quarter of the prior year.
Depreciation and amortization decreased slightly to $17.9 million in the second quarter of 2021 compared to $19.6 million in the second quarter of the prior year as capex has remained relatively low.
Our Technical Services segment revenues for the quarter increased to 118.7% compared to the same quarter in the prior year due to significantly higher activity and some pricing improvement.
Segment operating profit in the second quarter of 2021 was $1.4 million compared to $34.1 million operating loss in the second quarter of the prior year.
Our Support Services segment revenues for the quarter increased 44.1% compared to the same quarter in the prior year.
Segment operating loss this year was $2.4 million compared to an operating loss of $1.9 million in the second quarter of the prior year.
On a sequential basis, our second quarter revenues increased 3.4% from $182.6 million in the prior quarter due to activity increases in most of our service lines.
Cost of revenues during the second quarter of 2021 was $145.8 million, relatively unchanged from the prior quarter.
As a percentage of revenues, cost of revenues decreased from 80.1% in the first quarter of this year to 77.2% to the second quarter due to a favorable job mix in several service lines as well as the impact of the CARES Act employee retention credit that we recognized during the quarter.
Selling, general and administrative expenses during the second quarter of 2021 decreased 3.9% to $29.4 million from $30.6 million in the prior quarter, and this was also due to the impact of the retention tax credit.
RPC incurred an operating loss of $1.2 million during the second quarter of 2021 compared to an operating loss of $10.5 million in the prior quarter.
RPC's EBITDA was $17.3 million during the quarter compared to EBITDA of $7.8 million in the first quarter.
Our Technical Services segment revenues increased by $3.5 million or 2% to $176.1 million in the second quarter due to increased activity levels in most of the segment's service lines.
RPC's Technical Services segment generated a $1.4 million operating profit in the current quarter compared to an operating loss of $5.8 million in the prior quarter.
Support Services segment revenues increased by $2.7 million or 26.8% to $12.6 million during the second quarter.
Operating loss was $2.4 million compared to an operating loss of $2.9 million in the previous quarter.
Second quarter 2021 capital expenditures were $14.1 million, and we currently estimate full year 2021 capital expenditures to be approximately $65 million, comprised primarily of capitalized maintenance of our existing equipment and selected growth opportunities.
At the end of the second quarter, RPC's cash balance was $121 million, and we remain debt-free.

Summary:
Second quarter of 2021, revenues increased to $188.8 million compared to $89.3 million in the second quarter of the prior year.
We approached breakeven per share results in the second quarter of 2021 compared to an adjusted loss per share of $0.10 in the second quarter of 2020.