Petersburg Paradox can end on any toss, even the fastest-growing company's upward trajectory can flatten in a flash.

WSJ: The Intelligent Investor: Facebook and the St. Petersburg Paradox

Built by NeuroSky and a Japanese partner, NecoMiMi is a set of catlike ears that perk up when the wearer's concentration intensifies, and flatten out when relaxed.

WSJ: Mind-Controlled Videogames Become Reality

Hong Kong's Hang Seng swung between gains and losses to flatten out at 21, 661.08.

NPR: Asian Stocks Rebound As US Recovery Doubts Ease

"Sometimes that's an interesting class because they'll say, 'I'd just flatten them, '" says Breit.

CNN: Dressed For Success