The Unseen Giant: IBM's Mainframe Business Continues to Thrive

IBM is often overlooked as a major player in the tech industry, but it has been quietly dominating behind the scenes for decades. Despite not selling consumer-facing products since 2005, IBM's mainframe business remains profitable and continues to handle an enormous volume of transactions.

The company made a deliberate decision to focus on high-margin services and consulting rather than low-margin PC sales. In 2005, it sold its Personal Computing Division, including the ThinkPad brand, to Lenovo for $1.75 billion. The deal marked a clean break from consumer-facing products, with IBM retaining only its mainframe business.

IBM's mainframes are not known for their speed, but they excel at processing massive volumes of transactions without losing any data. The latest model, the z17, announced in April 2025, boasts impressive performance and can handle up to 450 billion inference operations per day at a response time of around 1ms.

The company claims that mainframes handle around 90% of the world's credit card transactions, with an estimated value of close to $8 trillion annually. This figure is not universally accepted, but IBM executives insist that their systems carry more than 70% of global transaction value.