Our performance was driven by our unique ability to combine IBM’s technology and expertise to create value for our clients and partners. We integrate IBM Software, IBM Consulting, and IBM Infrastructure to deliver this value.
IBM Software allows clients to leverage the full power of hybrid cloud and AI. Software revenues were up 4% at constant currency. Red Hat continues to gain momentum, growing nearly 21% at constant currency in the fourth quarter, benefiting from its integration with IBM’s portfolio and reflecting strong demand for open source innovation.
IBM Consulting revenues were up 8% at constant currency, driven by clients that rely on IBM as their trusted partner for digital transformation.
IBM Infrastructure revenues declined 3% at constant currency, reflecting product cycle dynamics. Clients continue to leverage our Power servers, storage, and IBM Z systems as foundational elements of their hybrid cloud infrastructure. In fact, we have shipped more MIPs in the z15 than any program in our history.
With this revenue and cash generation, we returned $6 billion to stockholders through dividends in 2021. We reduced debt by $10 billion in 2021 and by $21 billion since acquiring Red Hat in 2019. We did all of this while we continued to invest in skills, innovation, and our ecosystem, including $3 billion on acquisitions in the year.