that support maintenance turnarounds, shutdowns and emergency mobilizations for industrial plants primarily located in the southeastern region of the US and that are based on its expertise in producing, delivering and installing fabricated steel components such as piping systems and pressure vessels. Through SMC Infrastructure Solutions, the telecommunications infrastructure services segment provides project management, construction, installation and maintenance services to commercial, local government and federal government customers primarily in the mid-Atlantic region of the US.
We intend to make additional opportunistic acquisitions and/or investments by identifying companies with significant potential for profitable growth and realizable synergies with one or more of our existing businesses. However, we may have more than one industrial focus depending on the opportunity. We expect that acquired companies will be maintained in separate subsidiaries that will be operated in a manner that best provides cash flows for the Company and value for our stockholders.
Overview
Operating Results
Consolidated revenues for the three months ended July 31, 2021 were $133.0 million, which represented an increase of $45.5 million, or 52.0%, from consolidated revenues of $87.5 million reported for the three months ended July 31, 2020.
The revenues of the power industry services segment increased by $30.0 million to $99.0 million for the three months ended July 31, 2021, from $69.0 million reported for the three months ended July 31, 2020. The revenues of this reportable segment of our business represented 74.4% of consolidated revenues for the three months ended July 31, 2021. For the three months ended July 31, 2020, the percentage share of consolidated revenues represented by this reportable segment was 78.9%. The industrial services business reported revenues of $30.2 million for the three months ended July 31, 2021. This amount represented an increase of $13.5 million, or 80.7%, from revenues of $16.7 million reported by TRC for the three months ended July 31, 2020. Revenues provided by this reportable business segment represented 22.7% and 19.1% of corresponding consolidated revenues for the three months ended July 31, 2021 and 2020, respectively.
Consolidated gross profit for the three-month period ended July 31, 2021 was $27.7 million, or 20.8% of the corresponding consolidated revenues, which reflected primarily the favorable impacts of the higher amount of consolidated revenues and favorable contributions from all three reportable business segments. For the three-month period ended July 31, 2020, the consolidated gross profit was $15.6 million, which represented approximately 17.9% of the corresponding amount of consolidated revenues.
Selling, general and administrative expenses for the three months ended July 31, 2021 and 2020 were $10.3 million, or 7.8% of corresponding consolidated revenues, and $9.1 million, or 10.4% of corresponding consolidated revenues, respectively.
Due primarily to the increase in consolidated pre-tax book income to $17.1 million for the three months ended July 31, 2021 from $7.0 million for the three months ended July 31, 2020, we reported increased income tax expense in the amount of $4.2 million for the current period. Income tax expense for the three months ended July 31, 2020 was $1.4 million.
For the three months ended July 31, 2021, our strong overall operating performance resulted in net income attributable to our stockholders in the amount of $12.9 million, or $0.81 per diluted share. For the comparable period last year, we reported net income attributable to our stockholders in the amount of $5.6 million, or $0.36 per dilutive share.
Consolidated revenues for the six-month period ended July 31, 2021 were $259.3 million; this amount represented a 75.7% improvement from the amount of revenues for the six months ended July 31, 2020. The revenues of the power industry services segment represented 75.6% and 79.7% of consolidated revenues for the six months ended July 31, 2021 and 2020, respectively. The industrial services business reported revenues of $56.8 million for the six months ended July 31, 2021. This amount represented an increase of $30.4 million, or 114.9%, from revenues of $26.4 million reported by this business for the three months ended July 31, 2020. Revenues provided by this reportable business segment represented 21.9% and 17.9% of corresponding consolidated revenues for the three months ended July 31, 2021 and 2020, respectively.
Consolidated gross profit for the six months ended July 31, 2021 was $51.4 million, or 19.8% of the corresponding consolidated revenues, which reflected primarily the favorable impact of higher consolidated revenues. For the six months ended July 31, 2020, our consolidated gross profit was $19.6 million, or 13.3% of corresponding revenues for the period.