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 AOL (NYSE:AOL) have lost 11% of their value today after the online pioneer reported its fourth-quarter earnings this morning. That report was solid on the surface, but came with disappointing projections for AOL's 2015 fiscal year.

So what: AOL's revenue  grew by 5% year-over-year to reach $710 million for the fourth quarter, which resulted in earnings of $0.92 per share. The bottom-line result came in well ahead of Wall Street's expectation  of just $0.72 in EPS, but AOL missed analysts' top-line estimate of $721.8 million. Display advertising declined  by 6% and subscription revenues also fell by 5%, but this was offset by a 6% uptick in search ad revenue and a 16% year-over-year improvement in third-party ad revenues.

Looking ahead, AOL is describing  2015 as an "investment year," that may see "disruption" over the first half. In plain English, this appears to mean that AOL will report weaker results as it refocuses its core brands, which AOL CEO Tim Armstrong intends  to build into "global platforms." AOL CFO Karen Dykstra predicted a high-single-digit drop  in domestic display ad revenue over the first half of the year, and overall revenue should drop by about 2% over the full year before rebounding to low- to mid-single-digit growth rates in later fiscal years. Armstrong also highlighted a "bring-your-own-data strategy" that will allow third-party advertisers and publishers to utilize their own advertising data platforms for their ad targeting campaigns.

Now what: For all its efforts to become a content juggernaut, AOL remains a company that lives off cash-cow subscribers. AOL executives have made bold proclamations for years in an effort to distract shareholders from the fact that the company still gets virtually all of its operating income from its subscribers. Fourth-quarter adjusted operating income before depreciation and amortization (adjusted OIBDA) came in at $156.7 million, with subscriptions contributing $141.5 million of that total.

While subscriber revenue no longer makes up more than 100% of AOL's adjusted OIBDA as it has in recent quarters, this appears to be primarily due to declining subscriber counts, as AOL's brand segment (which include Huffington Post and other content sites) only grew its revenue by $900,000 year-over-year. It's also worth noting that AOL's strong EPS beat was -- as pointed out  by Jim Cramer in a CNBC segment this morning -- generated primarily by favorable tax rates, as the company's tax rate on pre-tax profits fell from nearly 50% a year ago to just 23% in the fourth quarter.

There's been no reason to be bullish on AOL as a long-term investment since its dial-up subscriptions became obsolete 15 years ago, and there appears to be no reason to be bullish today following the company's latest earnings report.

Alex Planes has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. 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 has a disclosure policy.