Sadly, there's no such thing as an ultimate buy signal when it comes to investing in stocks. Identifying companies with the wind at their backs takes time, patience, and a good dose of due diligence.

There is, however, an easy way to increase your odds of finding the stocks that will beat the market. At Motley Fool CAPS, the Fool's investing community of more than 135,000 members, we've found that our "five-star portfolio" is up 15.31% between January 2007 and April 2009, compared to a loss of 40.6% for the S&P 500.

To fully capture the upside potential of those highly rated stocks, it makes sense to identify them just as soon as they are upgraded to four- and five-star status. Fortunately, our CAPS screener now makes it possible to do this. Below, for example, is a list of companies that have been upgraded to four-star status from three stars just yesterday. These stock ideas are only a starting point, of course. Be sure to join us on CAPS to dig in even further.

Company

All-Stars Saying Outperform

Lindsay Corp (NYSE:LNN)

269 of 297

iShares Dow Jones US Oil & Gas Exp.(ETF) (NYSE:IEO)

138 of 142

j2 Global Communications, Inc. (NASDAQ:JCOM)

390 of 413

Itron, Inc. (NASDAQ:ITRI)

473 of 494

AeroVironment, Inc. (NASDAQ:AVAV)

490 of 515

Delta Petroleum Corp. (NASDAQ:DPTR)

246 of 260

Data from Motley Fool CAPS, July 10, 2009

Come join us on CAPS, absolutely free, to learn more about these and countless other interesting stock ideas.