For years, central banks have been the key to success in the stock market, and today's 127-point rise in the Dow Jones Industrials (DJINDICES:^DJI) owes much to the European Central Bank's actions today. By reducing a key interest rate by a quarter-percentage point to 0.5%, the ECB joined the Fed, the Bank of Japan, and other central banks around the world in pushing the pedal to the metal to try to stimulate the global economy. Moreover, the U.S. saw good news on the employment front, as jobless claims fell to their lowest levels in five years, and the trade deficit narrowed.

Despite the positive news, a couple of Dow stocks posted declines. Coca-Cola (NYSE:KO) lost 0.6%, pulling back from its highest levels in more than a decade. Ongoing worries about where the beverage giant will find new growth have lingered for a while, but if strength in emerging markets returns, then Coke stands to be among the biggest beneficiaries. Still, if a stimulus-led bull market resumes in earnest, then stocks that investors traditionally look to as defensive plays, such as Coca-Cola, could lag behind more economically sensitive companies.

Meanwhile, UnitedHealth (NYSE:UNH) dropped 0.4%. One big question that has arisen in light of the evolving implementation of Obamacare is the extent to which major health-insurance providers will offer coverage on state insurance exchanges. Given that the incentive of bringing in new premium revenue was supposed to offset more onerous policy requirements for UnitedHealth and other insurers, any failure to see increases in customer counts could leave the industry reeling from the new law.

Beyond the Dow, home-solar installation specialist SolarCity (NASDAQ:SCTY.DL) fell 3% after having been down as much as 14% near the open. The company suffered from an analyst downgrade that focused largely on near-term pressures to the solar installation business. Yet, the stock likely cut its losses due to the favorable long-term opinion from the analyst. Given that the industry has been moving toward an edge-power focus, SolarCity's business model remains an attractive way to play solar energy.

Finally, Boston Beer (NYSE:SAM) plunged 11% after reporting high expenses that wiped out gains in revenue. Between higher spending on promotions and advertising, and rising input costs, Boston Beer continues to face a highly competitive market, and will have to do its best to walk the line of catering to craft-beer enthusiasts while using its scale to its advantage.