Stocks hung flat in quiet trading for most of the day before all three major U.S. indices dropped after the Federal Reserve issued a statement following the end of its latest two-day meeting. As of 2:30 p.m. EDT, the Dow Jones Industrial Average (DJINDICES:^DJI) had fallen by more than 23 points, and most of the Dow's blue-chip member stocks have fallen into the red. Those losses have been offset by UnitedHealth Group (NYSE:UNH), which has soared 2.6% as part of a spirited day from the health insurance industry. Let's catch up on what you need to know.

Obamacare keeps rolling on
The Fed's biggest impact on the market was over interest rates: The central bank announced it would no longer use the unemployment rate as a benchmark for tapering and as a gauge of how the economy's doing, relying instead on a broad set of economic measures. Thirteen of the Fed's policymakers said they saw next year as a likely point to begin raising interest rates again, something the markets haven't taken kindly to after the years of post-recession record low rates.

UnitedHealth's stock shot up as shares from leading insurers across America have enjoyed a big bounce. The Department of Health and Human Services kicked things off by reporting that 5 million Americans have signed up for health insurance under the Affordable Care Act's exchanges since the law launched last October. It's been a strong run-up for Obamacare after a tepid start, and today's new height marks a million-member gain from the end of February.

While the administration still needs another 1 million enrollees in the final two weeks of its initial launch window to reach its revised goal of 6 million -- a tough hurdle to leap, and one that's still below the original White House objective of 7 million sign-ups through the end of March -- the gains have been good news for UnitedHealth and other leading insurers.

More members in the system will help alleviate feared rising costs from the new law, UnitedHealth's medical costs have grown at an equal or faster rate to premium growth in each of the last two years, with the 11% uptick in 2013 matching the company's total revenue growth for the year.

Elsewhere on the markets today, solar power company First Solar (NASDAQ:FSLR) stock has jumped 20%. The company announced full-year guidance today that foresaw 2014 sales coming in at up to $4 billion, a mark that impressed investors. The company also released its quarterly earnings, notching a per-share profit of $0.28 that marked a big swing from last year's $1.30 per-share loss. The company has been skyrocketing over the past year as one of the leaders of the nascent solar power niche, and if First Solar can deliver, investors who bought in early will profit in a big way.

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