The possible return of the uptick restriction on short-sellers of shares and the prospect of changes in an accounting rule that has forced banks to take billions of dollars in writedowns, sent U.S. shares higher on Tuesday.

U.S. Federal Reserve Chairman Ben Bernanke said he supported the mark-to-market accounting goal of making financial balance sheets as transparent as possible but thought there was room for improvement.

It's one of the things that tends at times to increase the severity of ups and downs in the financial system and the economy, he said in response to an audience question following a speech to the Council on Foreign Relations.

Barney Frank, who chairs the U.S. House of Representatives Financial Services Committee, predicted changes to mark-to-market given Bernanke's comments and said he hoped the uptick rule would soon be reinstated by the Securities and Exchange Commission.

I've spoken to Chair (Mary) Schapiro of the SEC. I am hopeful the uptick rule will be restored within a month, Frank told reporters.

U.S. shares were up about 5 percent as financial stocks got a boost from the regulatory developments and Citigroup said it was profitable in the first two months of 2009.

The SEC later confirmed it would consider reviving the uptick rule.

The Commission may conduct a public meeting as early as next month to consider whether to formally propose reinstatement of the uptick rule, or consider other measures related to short sales, said SEC spokesman John Nester.

Senate Banking Committee Chairman Christopher Dodd said he backed the SEC reinstating the uptick rule I wish they'd do it quickly, the Connecticut Democrat told reporters.

The uptick rule, adopted after the 1929 stock market crash, allowed short sales only when the last sale price was higher than the previous price. The SEC abolished the rule in 2007, after concluding that advances in trading strategies rendered it ineffective.

Short-selling is often blamed for precipitous declines in certain stocks but short-sellers defend their role, saying they prevent shares from becoming overvalued.

The SEC adopted emergency restrictions on short-selling last year but the measures were judged by some market watchers to have been largely ineffective.

Short-sellers borrow stocks they expect will fall in price in the hope of repaying the loans for less and pocketing the difference.

REGULATORY REFORM

Bernanke also said leaders from the Group of 20 rich and developing economies should agree early next month on principles to guide nations as they revamp financial rules to prevent future crises.

Finance ministers from the G20 meet this weekend in London to lay the groundwork for an April 2 leaders summit where regulatory reform is expected to feature prominently.

It's asking too much for a meeting like that to come out with detailed proposals in many different areas, Bernanke said.

Bernanke's remarks come two days before a U.S. House Financial Services subcommittee is scheduled to meet to consider possible changes to the mark-to-market rule.

Business groups have been pleading with the SEC and the Financial Accounting Standards Board to suspend or amend the rule so banks can account for hard-to-value assets more favorably amid distressed markets. The banking industry says the rule is undermining the federal government's $700 billion program to stabilize the financial industry.

But the SEC, which oversees and enforces accounting policy, is not planning a suspension, of mark-to-market, a source familiar with the matter told Reuters. The source was not authorized to speak on the matter and requested anonymity.

The SEC declined to comment.

GUIDANCE NEEDED

Bernanke emphasized that he was opposed suspending mark-to-market accounting, but given what is going on in the world, we should look to identify the weak points of mark-to-market and try and make some improvements on a more expeditious basis.

We need to do a lot more to provide guidance to the financial institutions and to the investors about what are reasonable ways to address valuation of assets that are being traded or if traded at all in highly illiquid, fire-sale type markets, Bernanke added.

Congress does not have the power to make outright changes in accounting rules. The SEC and the Financial Accounting Standards Board have said they are working on more guidance to help banks determine values of assets in illiquid markets.

Thursday's hearing, to be chaired by Pennsylvania Democrat Paul Kanjorski, will try to find fair-minded, incremental and achievable fixes to the mark-to-market accounting rule, the lawmaker said last week.

But the top Republican on the Senate Banking Committee, Richard Shelby of Alabama, said he opposed easing the mark-to-market rule.

Accounting rules should be designed to ensure that a firm's disclosures reflect economic reality, however ugly that reality may be, Shelby said at a committee hearing on investor protection issues.

(Additional reporting by Kevin Drawbaugh and Mark Felsenthal; Editing by Tim Dobbyn)

Citigroup Ben Bernanke