Warren Buffett is notoriously averse to investing in the tech industry, but the Oracle of Omaha nonetheless made a big investment in IBM (NYSE:IBM) stock in November 2011, and he has added to the position in recent quarters. In fact, Buffett publicly disclosed that he bought more IBM stock in the first quarter of 2015.

IBM has materially lagged the market over the last several years; the stock is down by 6% since November 2011, while the S&P 500 index gained 67% over the same period. Making the comparison look even worse, tech giant Apple's (NASDAQ:AAPL) stock has gained  a massive 118% since November 2011.

IBM Chart

IBM data by YCharts.

In this context, Rhonda Schaffler, editor-at-large at TheStreet and anchor of TheStreet TV, recently asked Buffett if he had any regrets about having picked IBM over Apple. His response was quite straightforward: "We don't think that way, we buy businesses we think we understand at prices we like, and then we hold them for a long time."

Why Buffett won't invest in Apple
Apple offers many of the traits that Buffett typically appreciates in a business. The company is the largest listed corporation in the planet, and Buffett needs to invest in companies that are big enough to have a material impact on Berkshire Hathaway's (NYSE:BRK-A) (NYSE:BRK-B) gigantic portfolio of assets.

Buffett is also all about competitive advantages, and Apple benefits from amazing brand power, one of the strongest and most sustainable sources of competitive strength. Apple is the most valuable brand in the world, according to Interbrand, which allows the company to charge higher prices for its products and deliver superior profitability for investors over time.

Its financial performance doesn´t leave much to be desired, either. Sales grew 27% during the last reported quarter, and earnings per share jumped by a jaw-dropping 40%. In case this were not enough for Buffett, the stock is attractively valued: Apple trades at a P/E ratio of about 17, a discount versus S&P 500 index average in the neighborhood of 20.

On the other hand, almost 70% of Apple's revenue during the last quarter came from sales of the iPhone, a product that did not even exist until 2007. Apple was a very different company 10 years ago, and chances are it will go through many more changes over the coming decade.

Apple has disrupted industries such as computing, music, and communications. This has been enormously beneficial for investors in Apple stock, but it could also be a source of risk going forward. Buffett likes to invest in companies strong enough to survive change, as opposed to those leading change in the world.

What Buffett likes about IBM
Buffett might not be a tech expert, but he understands a thing or two about the business world. When a company is looking for important solutions in key areas such as infrastructure software or security, the vendor's reputation and trustworthiness are crucial considerations. There is an old saying in the industry: "Nobody ever got fired for buying IBM."

In a recent interview with CNBC, Buffett said his experience and access to information across the business world provide an optimistic vision about IBM: "As I talk to CEOs and managers, I feel pretty good about IBM's future".

Companies such as Wells Fargo, American Express, and BNSF Railway are part of Berkshire Hathaway's portfolio, and they also big clients of IBM. That's why IBM is another prominent name in Berkshire's portfolio. In Buffett's brilliantly simple language, "We pay a lot of money to IBM every year, and we are very likely to continue paying them a lot of money."

Buffett does not need to understand every last specific detail about the kind of technologies IBM provides to its clients. He knows major corporations around the world rely heavily on IBM for critical services and solutions, and this is unlikely to change anytime soon.

IBM is also doing an amazing job at returning capital to investors; The company has increased dividends over the last 20 consecutive years, including a recently announced 18% payout boost for 2015. Over the last decade, IBM has reduced the amount of shares outstanding by a whopping 40%, so it is aggressively using both dividends and buybacks to reward shareholders. 

Keeping these considerations in mind, it's no wonder Warren Buffett finds strong reasons to invest in IBM for the long term.