(Bloomberg) — It’s been the best start to a year for hedge funds in a decade, and the returns for the biggest multi-strategy money managers are in. Ken Griffin, who runs the $30 billion hedge-fund firm Citadel, is beating his largest rivals, gaining 13.6% in the first six months of the year in his flagship funds, according to a person with knowledge of the matter. Those funds, Kensington and Wellington, are market neutral — so their bullish wagers are matched by bearish ones. All five of the strategies that feed into them made money over the period, said the person.