LONDON--Investors pulled more than $4 billion from Brevan Howard, one of the world's largest hedge funds, in the second half of 2016. Brevan, run by Switzerland-based British billionaire Alan Howard, experienced about $4.4 billion of outflows in its flagship Master fund in the six months to end of December, according to calculations by The Wall Street Journal based on letters to investors. The Master fund was once widely regarded as the gold standard for the hedge fund industry because of its impressive record. It racked up 11 consecutive calendar years of gains to 2013 including large double-digit profits during the...