About 100 small banks have stopped reporting financial details about their operations to the Securities and Exchange Commission since April, when a law was enacted that aimed to lower the regulatory burdens for small companies.

For nearly five decades, securities law allowed banks with fewer than 300 shareholders to “deregister” — meaning they could stop reporting to the SEC their revenue, expenses, executive compensation and trends affecting their businesses, among other things.

Now, banks with fewer than 1,200 shareholders can deregister under a provision of the Jumpstart Our Business Startups, or JOBS, Act. Since the threshold rose in April, 101 banks have rushed to take advantage of it — more than the total number of deregistrations for the previous 21 quarters combined, according to an analysis by SNL Financial. Eighteen of the banks are based in Virginia, the highest number of any state.

Most of the firms are small community banks with less than $500 million in assets. The banks say that reporting to the SEC is a time-consuming and expensive process that eats into thin profit margins without any meaningful benefit to the public. The industry remains heavily regulated even without SEC oversight, bankers say.

“I’m the happiest person in the bank because we’ve deregistered,” said Alan Dickerson, chief financial officer of the Bank of Floyd, a state-chartered bank southwest of Roanoke that is the sole subsidiary of Cardinal Bankshares Corp. But “I still have a lot of people looking over my shoulder.”

Bank deregistration jumps in 2012.

Critics of the higher thresholds say it’s true that some banks may be regulated by several institutions, including the Federal Deposit Insurance Corp., the Federal Reserve and state entities. But those regulators serve different constituencies whose interests do not always overlap, they said. The SEC is tasked with looking out for investors.

Making it easier for firms to avoid issuing key disclosures to the investing public will only lead to more fraud, investor advocates and lawmakers said.

“Shareholders should always be concerned when companies they invest in are allowed to operate behind a veil,” said Amy Borrus, deputy director of the Council of Institutional Investors.

The industry has been lobbying for years to get rid of the thresholds, which were put in place in 1964. The premise of that law is that companies with stock that’s widely held should disclose basic information about themselves, even if they’re private.

Over time, the older banks kept bumping up against that 300-shareholder limit. As longtime customers died, their stock was parceled out to heirs and other people. The shareholder count ballooned, forcing some banks to make public disclosures.

The issue was of such great concern to so many banks that they would often go to smaller shareholders and buy back the stock to keep from going over the limit, said Chris Cole, a senior vice president at the Independent Community Bankers of America.

Recognizing that banks already report to several regulators, the JOBS Act carved out an exception allowing them to deregister if the shareholder count fell below 1,200. All other companies must still abide by the old 300-shareholder limit.

Chris Brockett, chief financial officer of Virginia Heritage Bank, said his Vienna-based firm spent about $200,000 annually to comply with SEC rules before it deregistered. It will not reap all that in savings because it continues to pay for independent audits and other steps, he said.

“But all in all, we saw it as a cost save,” Brockett said. “That’s the biggest reason we did it. We are so regulated and so transparent that we didn’t see a big risk in it.”

Bill Ridenour, president of Reston-based John Marshall Bank, said his institution considered whether its 900 shareholders might balk at the bank’s decision to deregister. But the investors are fine with it, he said.

“We’ve gone out and raised capital from people that we do business with, that we’ve known for many years,” said Ridenour, who expects his bank to save $100,000 annually. “If we were a much larger company and they didn’t know us, that might be a different story.”

As an investor in banks, Joshua Siegel said he is not concerned. The chief executive of StoneCastle Partners in Manhattan said he’d rather see a bank’s money invested in new technologies or products rather than regulatory paperwork, especially since banks must disclose detailed financial data about themselves in “call reports.” Those reports do not include some of the details the SEC requires, such as executive compensation or the management’s analysis of business risks.

“But you’re not facing a drought as an investor for financial information on any bank, public or private,” Siegel said.

Still, critics of the new thresholds say the more information, the better. They’re worried because banks have a history of issuing partial or distorted data to their shareholders. The SEC is uniquely positioned to demand internal auditing controls.

As for the shareholders themselves, there are more of them than the public might think.

In the old days, the shareholders of record were individuals who held stock. But now they can be companies, such as ETrade or Merrill Lynch, that count as one shareholder even though they may represent tens of thousands of individual investors.

Sen. Jack Reed (D-R.I.) offered an amendment to the JOBS Act that would have forced the shareholder count to reflect each individual. But that amendment failed, along with a similar one offered by Sen. Carl Levin (D-Mich.).