In every bull market, there comes a time when nothing can seem to stop stocks from rising. It looks like we're in that phase now, as the Dow Jones Industrials (DJINDICES:^DJI) overcame an early morning decline to finish the day up 49 points. Both the Dow and the S&P 500 set new record highs, and even on the world-stock front, strength on the economic front from China and Germany has helped send one global stock benchmark to a new five-year high despite the weakness in Europe. Basically, what we've seen is that in the absence of news to the contrary, the path of least resistance appears to be upward.

UnitedHealth (NYSE:UNH) was the biggest gainer in the Dow, rising more than 3%. With no important news concerning the company, it's hard not to look back at the last time UnitedHealth rose for no explicable reason. Last month, the stock soared 3% late in the day, only to jump even further the next day when the federal government announced Medicare Advantage payment rates would unexpectedly rise rather than fall. So far, there's nothing to suggest any similar bombshell is imminent, although a recent Wall Street upgrade of health insurers could be what's creating some optimism about the sector.

Alcoa (NYSE:AA) rose almost 3% as the international economic news benefited it more than many of the Dow's components. As the producer of a commodity metal, Alcoa needs conditions in the key markets it serves to improve. That makes it particularly sensitive to positive economic news throughout the world, and with the strategic moves Alcoa has made to try to get through the tough times, investors are hoping that better economic times will finally lift the stock out of its doldrums.

Outside the Dow, obesity drugmaker VIVUS (NASDAQ:VVUS) soared almost 10% after releasing earnings this morning. Although its Qsymia diet pill didn't sell well, with overall revenue of $4.1 million coming in well below analyst estimates, VIVUS said that it's talking with larger pharma companies to try to find better ways to market and encourage more extensive use of the drug. With many short sellers betting against the stock, any good news from its strategic plans could lead to a squeeze that could produce even further gains.

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.