Five years after the financial crisis began to unfold, questions are arising about whether federal securities regulators are running out of time to pursue alleged fraud.

The answer, as usual, depends on who you ask.

Some courts have ruled that the Securities and Exchange Commission can only obtain civil penalties for fraud within five years of the activity taking place. More recently, the influential federal district court in Manhattan ruled that time runs out five years after the SEC discovers or should have discovered the alleged fraud.

Either way, the agency is pressing up against deadlines — at least in matters that arose early in the financial crisis, which erupted in mid-2007, legal experts said.

“Certainly, when you get near the statute of limitations, you can see them move more quickly, and the SEC is putting a lot of emphasis and manpower into its investigations,” said H. Rodgin Cohen, a partner at Sullivan & Cromwell.

The urgency may have to do as much with public demand for accountability in the financial meltdown as it does with deadlines. The SEC has charged 110 entities or individuals in financial crisis-related cases and collected $1.6 billion in penalties, the agency said. For instance, within the past two years, Goldman Sachs agreed to pay a record $550 million penalty and JPMorgan Chase agreed to a $153.6 million sanction. The government has not disclosed how many other probes are underway or who’s being investigated.

But for whatever’s left in the pipeline, there are ways to get more time if needed.

For cases under active investigation, the SEC can negotiate “tolling agreements.” Under those arrangements, firms or people under investigation agree to waive the five-year limit — or else.

“There’s always this moment when the SEC says: ‘You enter into this tolling agreement or we sue you tomorrow,’ ” said John C. Coffee Jr., a law professor at Columbia Law School who specializes in security regulation. “Most defendants prefer to enter into this type of agreement and avoid a dramatic event such as a lawsuit.”

Aside from sullying the defendant’s reputation, a lawsuit also could force the SEC to air allegations that turn out not to be justified, legal experts said. It’s often in the interest of a firm or individual to give the SEC time to sort through the facts, they said.

For all those reasons, as the five-year anniversary of the financial crisis approaches, several lawyers say they’ve seen an uptick in tolling agreements.

“They clearly understand they’re running out of time,” said Robert J. Anello, a partner at Morvillo, Abramowitz, Grand, Iason, Anello & Bohrer in New York. “The sense from my practice is that they are seeking [tolling agreements] in a number of cases.”

Still, there’s plenty of incentive for the SEC not to drag its feet.

Memories fade, evidence vanishes and witnesses disappear as time passes, eroding the agency’s ability to mount a successful case, agency officials said.

Taking action closer to the time of wrongdoing also deters similar fraudulent activity and makes it easier to compensate victims. Unlike many other agencies, the SEC can use penalties it collects to pay wronged investors instead of sending the money to the U.S. Treasury.

“The older the case, the greater the sense of urgency,” said George S. Canellos, deputy director of the SEC’s enforcement division. “But there’s not much connection between that sense of urgency we try to bring to our program and the statute of limitations.”

The Manhattan district court’s view of the five-year deadline could provide federal officials some breathing room, since it says the clock starts ticking at the moment that they discovered or should have discovered the alleged wrongdoing. But legal experts and SEC officials said it would be a risky strategy to rely too heavily on this reasoning because the relevant moment might not be clear.

“They’d rather be on the safe side of the five years than the guessing side,” said Tom Gorman, a partner at Dorsey & Whitney in the District.

All these investigations are taking place at what SEC Chairman Mary Schapiro recently described as a time of “enormous change and challenge” for the agency as it deals with the fallout from the financial crisis and new corporate accounting rules adopted in 2002.

Last fiscal year, the agency filed 735 enforcement actions — more than it has ever filed in a single year. This year, the agency is on track to settle the highest number of cases since 2005, driven largely by settlements with individuals for allegations related to insider trading and Ponzi schemes, according to NERA Economic Consulting. The SEC recently said it is litigating about 90 cases out of its Washington headquarters, up more than 50 percent from the previous year.