Hedge funds have increased their exposure to diesel and moved away from gasoline amid fears the lingering epidemic and slow vaccination programmes will depress personal travel and the services sector for many more months. Hedge funds and other money managers purchased the equivalent of 8 million barrels in the six most important petroleum futures and options contracts in the week to Feb. 2. But the rate of buying was the slowest for five weeks and before that the beginning of November, when the first successful vaccine trials were announced .