IBM has run a very aggressive stock buyback scheme for the past few years. Even while their revenues have decreased for 14 straight quarters, they returned $50 billion to shareholders through stock buybacks. They paid for most of this by issuing new debt and manipulating their accounting.

Imagine what they could have accomplished if they invested this into R&D instead.

They've given a huge amount of wealth to their shareholders at the expense of future growth. They can't sustain this much longer.

Some charts illustrating this from 2014 - http://www.zerohedge.com/news/2014-04-17/great-stock-buyback...

And them manipulating their finances http://www.zerohedge.com/news/2015-04-20/ibm-reports-worst-s...

buffett also likes companies with a "moat", which (arguably) IBM's patent portfolio provides.

Also they can borrow at incredibly cheap rates, which makes them useful as a financial company. (like GE / GE Capital)