NEW YORK (CNN/Money) - The deadline for the chief executives and chief financial officers of hundreds of large U.S. corporations to swear by the accuracy of their financial statements came and went with few surprises Wednesday.

Although a few companies told the Securities and Exchange Commission they could not meet the requirement due to extraordinary circumstances, many of the executives of some 700 companies that were required to sign off on their results by 5:30 p.m. EDT Wednesday did so.

But it was unclear late Wednesday exactly how many of them did not sign. The SEC did not release a final tally.

The SEC imposed the rule following a series of high-profile corporate accounting scandals at companies such as bankrupt energy trader Enron and telecom service provider WorldCom, which also has filed for federal bankruptcy protection.

Only companies with revenue of at least $1.2 billion in their latest fiscal year were required to certify their results. Companies that are incorporated outside of the U.S., even if they are essentially U.S.-based companies with foreign headquarters for tax purposes, also do not have to certify.

There had been some questions about whether several companies that recently have been tangled up in accounting troubles would be able to meet the SEC's deadline. And some of them did not.

Dynegy (DYN: up $0.20 to $1.50, Research, Estimates) late Wednesday said it has certified its financial results for the most recent quarter but it will not be able to do so for its prior financial statements until it completes a previously announced restatement of some of those numbers.

The energy trader is under investigation for allegedly making "round-trip" energy trades, in which transactions are made between energy traders simply to generate the appearance of robust business and, in some cases, to boost revenue.

A Dynegy spokesman told CNN/Money the company's top executives do plan to certify the prior results once the new audit and restatement has been completed.

Bankrupt cable operator Adelphia Communications also told the SEC it will not be able to certify its latest results. The company said it will not have audited results until later this year, when its new auditor, PricewaterhouseCoopers, completes its review. The company's founder, John Rigas, and two of his sons recently were arrested and charged with using the company as their "personal piggy bank," withdrawing hundreds of millions of dollars.

"An investigation by the Special Committee of the Adelphia Board of Directors into the Rigas family's breach of fiduciary duties and mismanagement is also under way at this time," said Erland Kailbourne, Adelphia's chairman and interim CEO.

"As previously stated, we believe the ongoing audit and the findings from these investigations will result in a restatement of Adelphia's financial statements for 1999 and 2000, as well as of interim financial statements for 2001," Kailbourne added. "Other periods may also be restated."

Energy holding company Nicor Inc. (GAS: down $0.20 to $27.26, Research, Estimates) also said it could not sign off on its 2002 financial statements because of uncertainties surrounding results of its gas distribution unit. The Naperville, Ill.-based company's financial results have been publicly in question since last month, when it became known that state officials were investigating allegations of accounting improprieties involving the way it recorded its natural gas purchases.

McLeodUSA, a local and long-distance telephone company that recently emerged from bankruptcy, said its executives had withheld certification of its 2001 financial information because it would have to restate results under the new accounting rules. The company, which did certify its results for the first and second quarters of 2002, said it is asking the SEC for a waiver of the re-audit requirement since the resulting financial statements would not be comparable with its ongoing operations.

Other companies of note that have had accounting problems recently and still have not signed off on their books include WorldCom, Qwest Communications, Reliant Energy, and CMS Energy. (An earlier version of this story incorrectly listed Omnicom Group Inc. among companies that had not signed off on their financial reports. In fact, Omnicom's chief executive and chief financial officer signed off on the company's results on Aug. 14.)

But as more and more companies stand by their finances, the new SEC rule has so far become something of a non-event for a stock market stung by a string of accounting scandals.

U.S. stocks staged a solid rally on Wednesday, driving the Dow Jones industrial average 3.1 percent higher while the tech-heavy Nasdaq logged a 5.1 percent gain.

Some say the extra layer of accountability will ease investor mistrust and flush out book cooking. Others call the measure cosmetic, saying the market won't recover without strengthening profits and a lot of time.

Morton Pierce, chairman of the mergers and acquisitions practice of Dewey Ballantine, says the rule will serve as a reminder that most business executives have not committed financial fraud.

"By and large, most people in the business community are ethical and are trying to do the right thing," said Pierce, who expects only a small number of restatements to emerge.

But Piece, like others, does not expect a quick market turnaround without an economic and corporate earnings recovery.

"In the long term, improving investor confidence is a marathon, not a sprint," John Gavin, of SEC Insight, told CNNmoney Morning.

The certification process brought to light some key information at several companies.

For example, when it announced that its top executives had signed off on that company's results AOL Time Warner, CNN/Money's corporate parent, pointed out that it had identified three transactions totaling roughly $49 million that may have been inappropriately recognized as advertising and commerce revenue.

Richard Parsons, AOL Time Warner's CEO, previously had expressed his opposition to the certification requirement.

The Pantry Inc. (PTRY: Research, Estimates), a North Carolina-based convenience store chain, voluntarily certified its results, even though it wouldn't have been required to until much later in the year. It said it uncovered a $8 million mistake in its accounts payable. The company said the mistake had no effect on its profits. (An earlier version of this report had an inaccurate figure and incorrect description of the mistake. CNN/Money regrets the errors).

Ad agency Interpublic Group (IPG: down $0.38 to $18.23, Research, Estimates) also signed off on its financial statements Wednesday but at the same time said it will restate more than five years of financial results after uncovering $68.5 million in improperly recorded charges.

Figuring out who missed the deadline may take a while. There is lag time between the arrival of the statements by fax and overnight mail and their posting by the SEC on its Web site.

"We are going to do it as quickly as we can," SEC spokesman John Heine said, adding he could not say how much time may elapse between the deadline and Web notification.

Companies can request a five-day extension on Aug. 15 if they don't meet the deadline. These extension requests should show up in the form of a filing on the free EDGAR database, Heine said.

A total of 947 companies with annual sales of more than $1.2 billion must file the sworn statement. About 250 of those companies can wait until November at the latest because of their non-calendar fiscal years.

"There's a lot of confusion," Robert Townsend, a corporate attorney with Morrison & Foerster, told CNNfn's The Money Gang.

Investors have been quick to punish companies that reveal improper record keeping. But it's not immediately clear what will happen to any companies that ignore the deadline.

While Susan Phillips, a former Federal Reserve governor, said she doubted that the new rules will have a major affect on the market, she believes they have value.

"It gets corporate executives focusing, thinking on some of these accounting issues that have been floating around," Phillips told CNNfn.

Jeffrey Skilling, the former CEO of Enron, told congressional investigators early this year that he had no knowledge of the financial problems that destroyed the company.