There is a reason why companies with big insider purchases tend to beat Wall Street expectations and it is not luck, said David Miller, portfolio manager for the Catalyst Insider Buying Fund. Miller's fund has outperformed the S&P 500 by more than 5 percentage points over the past year. Miller said he is seeing big insider buying in energy sector names like Consol Energy and Chesapeake due to management optimism about production growth in America. Finally, Miller said investors should avoid high-multiple, "story stocks" like Twitter, Tesla and Groupon because of the big bursts of insider selling associated with lock-up expiration.