The banking industry is also expected to keep up its fight against the rule. Wall Street lobbyists opposed the Volcker Rule more fiercely than any other regulation that has come from the Dodd-Frank law, which Congress passed in 2010. They argued that trading was not a primary cause of the financial crisis and that the Volcker Rule could actually prevent banks from carrying out safe activities, like hedging against risks.
Now that the final version of the rule has emerged, lawyers and lobbyists are likely to seize on the fuzzy nature of proprietary trading, which can resemble more legitimate forms of trading essential to doing business on Wall Street.
The rule, for example, allows banks to buy and sell securities if they show that the purchases are to meet the demands of their customers, a practice known as market-making. But banks, under the guise of market-making, could build a proprietary position in shares of Google, for example, contending that at some point clients might buy the shares.
The question is whether the wording of the Volcker Rule is strict enough to force banks to stockpile securities only for customers. The version reviewed by The Times shows that while regulators adopted some measures to prevent banks from masking their proprietary bets as market-making, the rule may still be vulnerable to evasion.
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Indeed, the rule says that banks can build up positions to meet "the reasonably expected near-term demands of clients, customers or counterparties." Banks and regulators may clash over what is "reasonably expected," and the rule leaves it largely up to banks to monitor their own trading.
The rule also allows banks to do proprietary trades in bonds issued by governments. United States banks can make bets with Treasuries and even municipal bonds. In a significant concession, the Volcker Rule allows the foreign affiliates of United States banks to trade in bonds issued by foreign governments.
Under the rule, banks can also place trades that are meant to offset the risks posed by positions they hold, an activity known as hedging that can resemble proprietary trading.
The five federal agencies writing the rule — the Federal Reserve, the Securities and Exchange Commission, the Commodity Futures Trading Commission, the Federal Deposit Insurance Corporation and the Comptroller of the Currency — were divided over how tough to make the hedging language.
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While some officials at the Fed and the S.E.C. have wanted to allow banks significant flexibility to carry out trading that is considered important for their health and the functioning of markets, Gary Gensler, the head of the Commodity Futures Trading Commission, sought to eliminate loopholes.
So when the Fed sent out a draft last month that removed a sentence that required hedging to be "reasonably correlated" with a bank's risks, people briefed on the matter said, Mr. Gensler and another agency commissioner, Bart Chilton, pushed back. And in recent days, they persuaded the Fed to insert into the rule a provision that requires banks to conduct a "correlation analysis" as well as "independent testing" to ensure that the trades used for hedging "may reasonably be expected to demonstrably reduce" the risks.
To further prevent banks from masking proprietary trading as a hedge, the rule required banks to conduct an "ongoing recalibration of the hedging activity by the banking entity to ensure" that the trading is "not prohibited proprietary trading."
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The votes on Tuesday, which come more than a year after Congress required the agencies to complete the Volcker Rule, offer Wall Street a degree of clarity that once seemed remote. Until recent days, regulators appeared unlikely to meet the recommendation of Treasury Secretary Jacob J. Lew, who urged the agencies to complete the rule in 2013.
"For the banks, this is one of the most significant regulatory changes in decades," said Alan W. Avery, a partner at Latham & Watkins who represents financial institutions in regulatory issues. "It cuts off or fundamentally alters traditional sources of revenue for the banks."