the same period last year. Selling and administrative expense, as a percentage of net revenue, was 18.5% compared to 19.3% in the prior year. Adjusted selling and administrative expense*, as a percentage of net revenue was 17.7% compared to 18.5% in the prior year.
Net income was $118.8 million, or $4.01 per diluted share, compared to $97.2 million, or $3.27 per diluted share in the prior year. Adjusted net income* was $161.0 million, or $5.44 per diluted share, compared to $128.9 million, or $4.34 per diluted share in the prior year.
For the full year of 2021, adjusted EBITDA* was $285.4 million, a 16.2% increase from $245.6 million in the prior year. Adjusted EBITDA, as a percentage of net revenue, was 14.5%, compared to 14.9% in the prior year. Operating income was $187.9 million, a 16.1% increase from $161.9 million in the prior year. The incremental adjusted EBITDA margin* on same branch revenue growth was 10.8% (please refer to the Supplementary Tables at the end of this Press Release).
Net cash from operating activities was $138.3 million, compared to $180.8 million in the prior year. The change in cash from operating activities was largely driven by increased inventory levels as a result of efforts to reduce material shortages combined with generally higher working capital needs in an inflationary environment.
Conference Call and Webcast
The Company will host a conference call and webcast on February 24, 2022 at 10:00 a.m. Eastern Time to discuss these results. To participate in the call, please dial 1-877-407-0792 (domestic) or 1-201-689-8263 (international). The live webcast will be available at www.installedbuildingproducts.com in the investor relations section or directly at https://viavid.webcasts.com/starthere.jsp?ei=1519780&tp_key=7f980bbecf. A replay of the conference call will be available through March 24, 2022, by dialing1-844-512-2921 (domestic) or 1-412-317-6671 (international) and entering the passcode 13725683.
About Installed Building Products
Installed Building Products, Inc. is one of the nation’s largest new residential insulation installers and is a diversified installer of complementary building products, including waterproofing, fire-stopping, fireproofing, garage doors, rain gutters, window blinds, shower doors, closet shelving and mirrors and other products for residential and commercial builders located in the continental United States. The Company manages all aspects of the installation process for its customers, from direct purchase and receipt of materials from national manufacturers to its timely supply of materials to job sites and quality installation. The Company offers its portfolio of services for new and existing single-family and multi-family residential and commercial building projects in all 48 continental states and the District of Columbia from its national network of over 210 branch locations.
Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the federal securities laws, including with respect to the housing market and the commercial market, our operations, our ESG initiatives and the expected impact thereof, industry conditions, our financial and business model, payments of a quarterly cash dividend and an annual variable cash dividend, the demand for our services and product offerings, trends in the large commercial business, the impact of the COVID-19 crisis on our business and end markets, supply chain and material constraints, expansion of our national footprint and end markets, diversification of our products, our ability to grow and strengthen our market position, our ability to pursue
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