Investors have built a billion-barrel bet on higher oil prices. But they are a different breed of bull than years past.  The “net long” position held by fund managers in crude oil futures is a powerful reflection of speculative sentiment. This year, the position has swelled to records of 1bn barrels equivalent across the main oil contracts, helping sustain prices above $60 a barrel.  Who trades oil is changing, however. Investors who bother little with details such as inventories and pipeline flows are replacing dwindling ranks of specialist commodities hedge funds. The shift could alter the way prices are formed.  The identities of oil investors are murky.

Futures markets, anonymous by design, have become more so because of electronic trading. Regulators shed some light by publishing weekly data on broad categories of trader, including money managers.  In recent years the number of money managers large enough to report positions has increased, reaching more than 100 in Brent futures on Intercontinental Exchange. This comes despite shutdowns of some of the biggest funds in oil markets, such as one run by Andy Hall of Astenbeck Capital Management.