Momentum investing is all about the idea of following a stock's recent trend, which can be in either direction. In the 'long' context, investors will essentially be "buying high, but hoping to sell even higher.

OSI Systems (NASDAQ: OSIS) -- now that's a blast from the past. It's been close to a decade since I last wrote about the maker of X-ray and metal detector systems for air traveler and cargo screening.

HAWTHORNE, Calif. (AP) — HAWTHORNE, Calif. (AP) — OSI Systems Inc. (OSIS) on Thursday reported fiscal second-quarter net income of $37.8 million. On a per-share basis, the Hawthorne, California-based company said it had profit of $2.22. Earnings, adjusted for one-time gains and costs, were $2.42 per share.