Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of online household name AOL (NYSE: AOL) are making waves today, jumping as much as 10.2% overnight before falling to a 2.5% loss amid heavy trading.

So what: First-quarter sales shrank 17% year over year to $533 million, which still was enough to impress analysts, but AOL's $0.04 of earnings per share fell far short of Wall Street's $0.26 target. It took investors some time to make heads or tails out of this conflicting data, especially since early headlines underscored a rare gain in advertising sales.

Now what: The domestic display ad segment was the only glimmer of growth in an otherwise uniformly deflating business, and the lack of sales power was exacerbated by rising content acquisition costs. When all is said and done, AOL is shaking off the trappings of its old subscription services and Internet access lines to become a purely ad-supported content portal in the very image of Yahoo! (Nasdaq: YHOO) -- which is another failing and flailing business model. Weren't we all supposed to replace unreliable ad revenues with dependable subscription services 10 years ago -- when AOL was still relevant? This is not going to end well for AOL, folks.

Interested in more info on AOL? Add it to your watchlist.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. Yahoo! is a Motley Fool Global Gains choice. The Fool owns shares of Yahoo!. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.