Shake Shack's stock soars as post-IPO lock-up period expires

Shake Shack Inc.'s stock rocketed 20% in active, afternoon trade Wednesday, putting it on track to post the biggest one-day price and percentage gain in its 6-month history. Volume of over 930,000 shares was nearly double the full-day average. The burger chain didn't release any news, and a company spokesperson was not immediately available for comment. Shake Shack went public 180 days ago, meaning the lock-up agreements for the underwriters, which restricted them from selling any of the shares, have now expired. The jump in Shake Shack's stock is likely a combination of the company's expiring lock up period, investors' confidence in the company's growth and short-sellers trying to cover their position, Peter Cohan, a venture capitalist and president of Peter S. Cohan and Associates, told MarketWatch. Short interest, or bearish bets in the stock was about 2.3 million shares as of mid-July, or more than triple what it was five months ago.

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