Whenever the Federal Reserve meets to discuss monetary policy, the stock market holds its breath as it tries to figure out whether the end to the central bank's massive interventions is in sight. Yet even with the broad-based policy issues overhanging the market, investors must also pay attention to the ongoing onslaught of earnings reports coming out. The net effect of those two factors is negative this morning: As of 10:50 a.m. EDT, the Dow Jones Industrials (DJINDICES:^DJI) have fallen falling 59 points, or 0.4%, while the broader market has dropped by a similar percentage.

Continuing yesterday's theme of bad news for health-care-related stocks, Merck (NYSE:MRK) is the biggest decliner on the Dow, falling 2.6% after releasing quarterly earnings that beat expectations but pulling back on its guidance for the full 2013 year. Merck now expects a range $0.15 per share lower than it had previously estimated. Potentially more troubling is the fact that revenue came in even weaker than expected, with 9% lower sales owing largely to the loss of patent protection for Singulair late last year. Nevertheless, even blockbuster Januvia saw weaker sales, although Merck's Gardasil STD vaccine saw 37% growth in revenue. Merck needs to keep its pipeline strong if it wants to replace lost revenue from Singulair and other drugs facing generic competition.

Alcoa (NYSE:AA) has also given up ground, posting a 1.9% decline after announcing that it will consider curtailing some of its smelting capacity in the next year and a quarter in response to weak aluminum prices. Given Alcoa's big role in the aluminum industry, its production decisions have a significant impact on market pricing, and the company hopes potential cuts that could affect 11% of its total smelting capacity will help reduce overall costs and improve profitability. The company already has 13% of its capacity idled, and given the ongoing uncertainty about global economic conditions, it seems likely that Alcoa will add to that total after its review.

Beyond the Dow, earnings news pushed individual stocks in both directions. On the upside, Trulia (NYSE:TRLA) has soared 12.4% despite missing first-quarter earnings estimates. The real-estate listing stock pushed up its quidance for second-quarter sales, and with the company having beaten revenue estimates for the first quarter, investors are clearly interested in seeing the company gain as much market share as possible, no matter the cost to current profitability. Meanwhile, Vonage (NYSE:VG) has sunk 6.2% after reporting a slight drop in GAAP net income. Revenue fell just more than 3%, for which the company cited fewer subscriber lines and increased use of lower-priced plans. Although the company expects to announce a new $9.99 per-month phone service in the near future, it's clear that Vonage is suffering from alternative providers offering even lower costs.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. 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.