The CFTC has expanded an investigation, disclosed previously by The Wall Street Journal, into alleged short-term manipulation of crude-oil prices via a widely used price-reporting system run by Platts, a unit of McGraw-Hill Cos. One suspicion is that energy companies and traders have at times issued a flood of orders during a time window used by Platts to determine its reported prices for physical oil transactions, then used the potentially distorted prices to make profits in other markets. Platts has said its system has safeguards to protect against manipulation. Subpoenas on the matter have gone out in several stages, people familiar with the cases say.
The agency has also been questioning traders about similar activity in the jet-fuel market, people familiar with the matter say.
Another area of concern for CFTC regulators is whether the owners of crude-oil storage tanks use their knowledge to make bets on oil-futures markets. In theory, the owner of a tank could issue misleading information about the tanks being full or empty, leaving the wrong impression about whether oil is in plentiful supply. Then they could make trades to profit on the misunderstanding.
Artificial Price - Unlike most stock markets, insider trading isn't generally illegal in commodities trading. An oil company can take advantage of inside information about its production outlook when it makes trades. However, if traders intentionally create an artificial price and use it to make money, charges of manipulation may arise.

The CFTC regulates one of the fastest-growing financial markets with a fraction of the budget of the Securities and Exchange Commission. In the past, critics have called it a weak enforcer, but its small enforcement staff has sought to bring more ambitious cases in recent years, particularly in the energy markets.
The CFTC doesn't oversee all U.S. commodities trading. Large speculators such as hedge funds often use unregulated over-the-counter platforms, whose prices may affect prices on regulated markets. Mr. Chilton, the CFTC commissioner, said regulators are looking at cases where traders have made simultaneous bets on unregulated and regulated markets, in particular in West Texas Intermediate crude-oil contracts. He said he wants to know "whether there's any possibility for attempted manipulations as a result."
Apart from its investigations into specific allegations, the CFTC said Thursday it will require more information in general from large traders. It wants to know about their bets in commodity-linked index investments as well as speculative trades that they are able to place via Wall Street dealers, often in large quantities.
The CFTC's acting chairman, Walt Lukken, said investors flooded into commodities after a credit crisis hit the financial markets last summer and risky bond investments lost popularity. "There was this enormous flight to safety," he said. "This is something we have to really drill down on in terms of where the money is coming from, and what its impact is on the markets."
He stressed that the CFTC's move to require more information from institutional investors is separate from any probes into illegal trading activity.
"I don't think anybody is indicating that index-fund investors, as a class, are causing broad illegal manipulation of the markets. It's a different issue from the crude oil investigation," he said.
The CFTC's chief economist testified to the Senate last week that CFTC data on large traders shows that price increases in commodities "are largely unrelated to fund trading."
"There's incredibly heightened scrutiny on these markets, and anybody who does business in these markets faces a lot of regulatory risks," said Paul Pantano, a Washington lawyer who represents many energy traders. "Commercial parties and speculators are operating in a market where the rules about what is considered manipulative conduct versus legitimate trading activity are not very clear."