Still, many in the industry warn against reading too much into one trading loss. They say losing money is an inevitable part of taking risk, as banks must.

Some fear that after JPMorgan’s announcement, regulators will greet industry concerns with more skepticism as they flesh out key parts of the overhaul law.

Here’s a look at four key parts of the financial overhaul and how they might be affected by JPMorgan’s losses:

THE VOLCKER RULE

This provision restricts banks’ ability to trade for their own profit, a practice known as proprietary trading. It is named for former Federal Reserve Chairman Paul Volcker.

— Battle lines: Banks say it disrupts two of their core functions: Creating markets for customers who want to buy financial products and managing their own risk to prevent major losses.

They say proprietary trading was not a cause of the 2008 financial crisis and the rule is a means of political revenge on an unpopular industry. Advocates of stronger regulation argue that the rule would have prevented JPMorgan’s loss. They say the trades were made to boost bank profits, not to protect against market-wide risk.

— State of play: A draft of the rule satisfied neither side. It includes exceptions for hedging against risk and for market-making, but banks say they the exceptions are too narrow and difficult to enforce. It’s nearly impossible to tell whether a bank bought or sold something for itself or for customers.

— JPMorgan effect: Attitudes about the Volcker rule are likely to shift as a result of JPMorgan’s disclosure, experts say. Even if JPMorgan’s trades truly were a failed attempt to protect against risk, the resulting loss strengthens the argument that regulators should err on the side of scrutinizing trades.

ENDING ‘TOO BIG TO FAIL’

During the 2008 financial crisis and the bailouts that followed, the government was unwilling to let the biggest banks fail, for fear of upending the financial system. As part of the overhaul, Congress created a process to shut down financial companies whose failure could threaten the system.

— Battle lines: Most players agree that this is a good idea, despite some differences on the details.

— State of play: The Federal Deposit Insurance Corp., the agency responsible for closing smaller banks that falter, has taken the lead on writing rules to shut down big firms. Most observers believe that the FDIC, under acting chairman Martin Gruenberg, is on track toward creating a system that markets would trust to close a big bank.

Banks have been working with regulators to create “living wills” detailing how they would wind themselves down without disrupting markets. This exercise has forced them to look more deeply at their operations — a defense against the accusation that banks have grown “too big to manage.”

However, U.S. regulators can’t do it alone. A big problem after the failure of Lehman Brothers investment bank in 2008 was what to do with its overseas operations. It wasn’t clear which regulators were in charge, or whose bankruptcy court would control the disposal of Lehman’s assets.

Regulators are negotiating with their European counterparts, but it could take years before they agree on rules that would allow a global company to dismantle itself without spreading confusion through the financial markets.

— JPMorgan effect: Like other banks, JPMorgan supports giving the government the power to dismantle a failing bank. CEO Jamie Dimon said so clearly in an appearance on “Meet the Press” on Sunday. JPMorgan’s loss probably doesn’t affect the likelihood that regulators will break up a bank in the future. The loss wasn’t nearly big enough to threaten JPMorgan with failure.

REGULATING DERIVATIVES

JPMorgan’s bets involved complex investments known as derivatives whose value is based on the value of another investment. Before 2008, many derivatives were traded as individual contracts between banks and hedge funds, without any transparency for regulators. The financial overhaul sought to bring more derivatives onto regulated exchanges and force derivatives traders to put up more cash in case their bets turned against them.

— Battle lines: Overhauling the rules governing this market, estimated at $650 trillion, has proved as complex as the investments themselves. Banks support many parts of the overhaul but generally argue that forcing too much transparency would make it harder and more expensive for companies to use derivatives as a hedge against risk. They say it is an unnecessary cost that would be spread across all types of companies.

The agency most responsible for implementing these rules, the Commodity Futures Trading Commission, faces the threat of a much smaller budget than it says it needs to write the rules and increase its oversight of the derivatives market.

Advocates for stronger regulation argue that the new rules apply to the sorts of derivatives believed to have magnified the financial crisis — and JPMorgan’s losses — but do not threaten investments like energy futures, for example, which airlines use to control fuel costs. They say banks are just trying to protect a lucrative business that other companies can’t compete in today.

— State of play: About half the rules are done, but many crucial questions have yet to be decided. The rules will be phased in this fall through next spring. Banks are lobbying hard to protect their hold on this profitable business. Banks support pending legislation that would limit U.S. regulators’ control over derivatives trades by their overseas affiliates.

— JPMorgan effect: Fairly or not, JPMorgan’s big loss on derivatives trades is likely to revive scrutiny of that market. That could give advocates of tighter rules some juice in ongoing negotiations with regulators. It also could empower those who believe the budgets of the CFTC and Securities and Exchange Commission should be increased to reflect the need for broader oversight.

BANK OVERSIGHT

The overhaul calls on the Federal Reserve to oversee the biggest and most important financial companies and apply a stricter set of standards for financial fitness. For example, the companies must hold more capital as a buffer against future losses. Before, the biggest banks were overseen by a patchwork of regulations.

— Battle lines: Industry officials say they’re working with regulators to fine-tune how big companies will be overseen. They are concerned, for example, about the extra costs imposed on the big companies to offset the extra risk they create in the financial system.

— State of play: Industry officials say many of these changes were happening behind the scenes even before the financial overhaul was passed in 2010. They say banks already are better capitalized and meet other standards laid out by regulators.

It’s still not known exactly which financial companies will fall into this category. The biggest banks are included automatically. Regulators have more discretion when it comes to what are known as non-bank financial companies, such as huge insurance companies. Companies on the margin reportedly are lobbying hard to avoid this designation.

— JPMorgan effect: As the nation’s biggest bank, JPMorgan automatically will face stricter oversight. The trading loss there is unlikely to affect detailed negotiations about how exactly such companies will be overseen.

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Daniel Wagner can be reached at www.twitter.com/wagnereports .

The trading loss is an embarrassment for a bank that came through the 2008 financial crisis in much better health than its peers. It kept clear of risky investments that hurt many other banks.

The loss came in a division of JPMorgan designed to help control its exposure to risk in the financial markets and invest excess money in its corporate treasury.

Bloomberg News reported in April that a single JPMorgan trader in London, known in the bond market as “the London whale,” was making such large trades that he was moving prices in the $10 trillion market.

Dimon said the losses were “somewhat related” to that story, but seemed to suggest that the problem was broader. Dimon also said the company had “acted too defensively,” and should have looked into the division more closely.

The Wall Street Journal reported last month that JPMorgan had invested heavily in an index of credit-default swaps, insurance-like products that protect against default by bond issuers.

Hedge funds were betting that the index would lose value, forcing JPMorgan to sell investments at a loss. The losses came in part because financial markets have been far more volatile since the end of March.

Partly because of the $2 billion trading loss, JPMorgan said it expects a loss of $800 million this quarter for a segment of its business known as corporate and private equity. It had planned on a profit for the segment of $200 million.

The loss is expected to hurt JPMorgan’s overall earnings for the second quarter, which ends June 30. Dimon apologized for the losses, which he said occurred since the first quarter, which ended March 31.

“We will admit it, we will learn from it, we will fix it, and we will move on,” he said. Dimon spoke in a hastily scheduled conference call with stock analysts. Reporters were allowed to listen.

Among other bank stocks, Citigroup was down 3.3 percent in after-hours trading, Bank of America was down 2.9 percent, Morgan Stanley was down 2.4 percent, and Goldman Sachs was down 2.2 percent.

JPMorgan is trying to unload the portfolio in question in a “responsible” manner, Dimon said, to minimize the cost to its shareholders. Analysts said more losses were possible depending on market conditions.

Dimon said the type of trading that led to the $2 billion loss would not be banned by the so-called Volcker rule, which takes effect this summer and will ban certain types of trading by banks with their own money.

The Federal Reserve said last month that it would begin enforcing that rule in July 2014.

Some analysts were skeptical that the investments were designed to protect against JPMorgan’s own losses. They said the bank appeared to have been betting for its own benefit, a practice known as “proprietary trading.”

Bank executives, including Dimon, have argued for weaker rules and broader exemptions.

JPMorgan has been a strong critic of several provisions that would have made this loss less likely, said Michael Greenberger, former enforcement director of the Commodity Futures Trading Commission, which regulates many types of derivatives.

“These instruments are not regularly and efficiently priced, and a company can wake up one day, as AIG did in 2008, and find out they’re in a terrific hole. It can just blow up overnight,” said Greenberger, a professor at the University of Maryland.

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AP Business Writer Pallavi Gogoi contributed to this report.

The labor market has been on traders’ minds all week; the big April jobs report is due out Friday. In the final major indicator before that announcement, the government said that the number of people applying for unemployment benefits fell last week by the most in three months.

GM shares fell 2 percent in early trading after the automaker said its first-quarter profit declined, mainly on losses in Europe. When people worry about whether Europe’s debt crisis will spill over into the U.S., one of the major threats is that the European recession will harm sales by big American exporters such as GM and Caterpillar.

Major stock indexes lacked direction, opening lower then rising slightly in the first 15 minutes of trading. For much of the morning, they traded solidly lower. The indexes were back near flat by midday.

The Dow Jones industrial average fell 10 points to 13,259 as of 11:30 a.m. EDT. The Standard & Poor’s 500 index fell two to 1,400. The Nasdaq composite index fell 10 to 3,050.

The Carlyle Group, a big, politically-connected private equity firm, edged higher after an initial public offering of some 30.5 million common units worth $671 million.

The company priced its stock at below the expected range late Wednesday. Carlyle, trading on the Nasdaq under the ticker “CG,” has about $147 billion in assets under management.

Other swinging stocks:

— Green Mountain Coffee Roasters Inc. plunged 46 percent, the most in the Russell 2000 index of small companies. The maker of single-cup coffee machines and cartridges said late Wednesday that its earnings for the fiscal year ending in September will be far below its previous guidance and analysts’ estimates.

— Cablevision Systems Corp. dropped eight percent after its first-quarter revenue fell short of analysts’ expectations and profit declined sharply.

— Viacom Inc., owner of MTV and Paramount Pictures, rose four percent after saying its net income rose sharply as its TV networks brought in more revenue.

— Orbitz Worldwide Inc. rose eight percent after narrowing its first-quarter loss, beating analysts’ estimates.

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Daniel Wagner can be reached at www.twitter.com/wagnerreports .