Dallas-based hedge fund Brenham Capital is closing, a casualty of what founder John Labanowski called “some truly bizarre stock action.” Brenham made bets on small and midcap energy stocks. Brent, the global benchmark, entered a bear market this month—defined as a 20% drop from a recent peak. Energy investors have also been whipsawed by volatility outside the oil market. Brenner West Capital Partners is also closing after 13 years in business, people familiar with the matter told The Wall Street Journal on Friday.