What happened

Shares of American Airlines Group (AAL -1.06%) took flight this morning, rising 5.7% in apparent response to a Securities and Exchange Commission filing on Tuesday in which it disclosed that publicly traded investment manager BlackRock (BLK) now holds a 4.8% stake in the company.  

If that is the reason investors are buying American Airlines stock today, figuring BlackRock knows something that the rest of us do not, then they may be making a big mistake.

American Airlines airplane in flight.

Image source: American Airlines.

So what

Digging into the company's filings on the SEC's website, it turns out that yesterday's report is not the first mention of BlackRock's ownership stake in American. In fact, the most recent filing prior to this one, from April 2020, showed that BlackRock owned a 5.5% stake in the airline.  

And prior to that, BlackRock's stake was 5.3%, in February.  

Now what

Viewed in context of these previous reports, therefore, it appears that what is happening here is not what investors think is happening -- i.e., BlackRock taking a new position in American, indicating optimism about the stock and perhaps about the prospects for airline stocks in general. Rather, it appears that BlackRock, having held a sizable stake in American Airlines all through the pandemic, is now beginning to pull out of the stock.

If what you are aiming to do today, therefore, is to imitate the smart money, then what you really might want to do is sell shares of American Airlines. And in fact, with the share price gains now pared to 2.5% as of 10:45 a.m. EST, this might be just what investors are doing.