For the second day in a row, international currency moves had a huge impact on the stock market. With the Japanese yen having broken above the 100 yen-per-dollar mark yesterday, the dollar continued its advance against Japan's currency again today, gaining another 1%. The news sent Japanese stocks soaring, commodities like gold and oil falling, and bond prices plunging. But for U.S. stock market investors, the news had a much less dramatic effect, with the Dow Jones Industrials (DJINDICES:^DJI) finishing with a gain of about 36 points, while the broader market posted slightly stronger gains.

Looking at the largest gainers in the Dow, two companies stood out for very different reasons. On one hand, UnitedHealth (NYSE:UNH) rose about 1.4%. Despite having no substantial news to justify the gains, UnitedHealth has benefited from increasing clarity about the impact of Obamacare on its revenue and earnings going forward. Moreover, as the market has soared, UnitedHealth's relatively low earnings multiple of just 12 looks increasingly attractive, especially in comparison to much higher-priced consumer stocks and other more traditional defensive plays.

Meanwhile, Hewlett-Packard (NYSE:HPQ) picked up almost 1.7% today. Lately, most of the news in the industry has centered on rival Dell (UNKNOWN:DELL.DL), which today included another round in the ongoing battle between activist investor Carl Icahn and Dell founder and would-be going-private buyer Michael Dell about the valuation of the company. Yet HP has quietly continued making its adjustments to try to take advantage of Dell's distractions, and so far, the stock has rewarded investors' patience with solid gains in 2013. HP still has a ways to go before it can declare victory, including fending off whatever Dell decides to do to try to boost its own competitive position, but things are finally starting to look up for HP after a horrific 2012.

Finally, beyond the Dow, rare-earth-metals miner Molycorp (NYSE:MCP) soared more than 30% after reporting a narrower-than-expected loss and gains in production output in its quarterly earnings. The company is still nowhere near profitability, but with a 73% boost in revenue and more than triple its year-ago sales in terms of volume tonnage, Molycorp just might be able to work through the poor pricing conditions in the industry.

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