In 1999, Congress permitted Wall Street investment banks like Goldman Sachs and Morgan Stanley to keep their commodity operations. Since then, other banks have been allowed to expand into commodities, but in recent years no bank has gotten more leeway from the Fed than JPMorgan, experts in the field contend. In California and the Midwest, JPMorgan’s subsequent dealings in electricity echoed actions of Enron a decade earlier. The Federal Energy Regulatory Commission contended that JPMorgan engaged in price manipulation that generated $125 million in “unjust profits.” Last July, JPMorgan agreed to pay $410 million in penalties and restitution; it neither admitted nor denied wrongdoing.

Maneuvering in markets for electricity, metals, oil and more added billions to the bottom line at banks like JPMorgan, Goldman Sachs and Morgan Stanley in recent years. But their involvement in commodities has now come under intense scrutiny. Industrial users of aluminum and other metals contend that questionable activities by major banks have increased their costs. Regulators like the Commodity Futures Trading Commission have been investigating the issue, and congressional hearings have also explored potential problems.

Amid this heightened scrutiny, the Fed said last July that it would review its recent decisions to let banks expand their commodities operations. A ruling is expected early next year. A Fed spokeswoman declined earlier this month to comment further. JPMorgan, for its part, has scaled back its activities in the electricity market and, last summer, said it was putting its entire commodities unit up for sale. The decision comes as prices — and profits — have fallen in the commodities arena.

The opposite held true in 2005, when banks began asking the Fed for the right to expand into commodities trading. The banks argued that this business was complementary to their financing operations and thus should be allowed. The Fed agreed.

In these rulings, the Fed consulted the Bank Holding Company Act, a 1956 law designed to protect banks and the financial system from risks associated with nonfinancial activities. The basic idea is that for banks, some businesses are simply too risky. An institution that owned oil tankers, for example, might be threatened by the costs associated with a large oil spill.