Mitch Rubin's fund has used a unique approach to reap 26% returns and double client assets this year. He breaks down his 3-part process for deciding which stocks to buy — and what to bet against.

· Mitch Rubin's mutual fund is up 26% this year thanks to a mix of bets on the right high-growth companies and short positions on vulnerable stocks.
· Investors want to get in on what he's doing, and the assets invested in his fund have more than doubled since March.
· He told Business Insider about the two must-have...