Warren Buffett may already be regretting his recent decision to aggressively build up big stakes in airline stocks. The investment guru, who just four years ago labeled the industry a “death trap” dominated by bankruptcies, took a hefty hit after a video of a passenger being forcibly removed from a United Airlines plane went viral. (See also: Did United Have the Right to Force That Guy Off the Plane?)

The Oracle of Omaha’s Berkshire Hathaway became the largest shareholder of United Airlines’ parent company United Continental Holdings (UAL) late last year, amassing 28.95 million of shares to bring his total stake to 9.2 percent of the company. That bold move, which was partly influenced by reduced competition in the industry following a series of mega mergers, has just turned out to be poor one, for now at least. (See also: Frequent Flyer Miles, the Hidden Lynchpin of Airline Sector.)

United Airlines’ treatment of a bloodied passenger led its parent company’s market valuation to plummet by nearly $1 billion. Based on its current share price of $69.93, Buffett has already lost about $90 million from this negative publicity.

Other big investors caught up in the chaos include investment manager BlackRock (BLK), passive investment specialist Vanguard and Primecap Management.

What Other Airlines Does Buffett Own?

Buffett's punt on the airline industry also saw him more than double his stake in American Airlines (AAL) to 45.54 million shares, increase his holding in Delta Air Lines (DAL) by nearly nine-fold to 60.03 million shares, and purchase a 43.20 million position in low-cost carrier Southwest Airlines (LUV). While sentiment in Delta and American has yet to take off since the end of 2016, SouthWest’s shares have made an encouraging start to the year.

In other news, Buffett recently sold 9 million of shares in scandal-hit bank Wells Fargo (WFC). Berkshire Hathaway confirmed that it was forced to give up some of its huge stake by the Federal Reserve, driven by concerns over Wells Fargo’s banking relationships with several of Berkshire Hathaway companies.

Want to learn how to invest?

Get a free 10 week email series that will teach you how to start investing.

Delivered twice a week, straight to your inbox.