By Svea Herbst-Bayliss and Steve Holland

BOSTON/WASHINGTON (Reuters) - Wall Street lawyer Jay Clayton, who has worked on high-profile initial public offerings such as Alibaba Group, is a leading candidate to head the U.S. Securities and Exchange Commission in the Trump administration, two sources familiar with the matter said on Tuesday.

Clayton is a partner at Sullivan & Cromwell who specializes in public and private mergers and offerings, an area that requires expertise on complex securities regulations and corporate governance.

Clayton was not available to comment.

He met with President-elect Donald Trump on Dec. 22 and appears to have overtaken a former U.S. Attorney, Debra Wong Yang, whose name had been floated as a top candidate in early December.

Yang declined to comment.

Clayton's name surfaced relatively recently and he is one of a handful of other top contenders. Besides Yang, other names mentioned include former SEC commissioner Paul Atkins, lawyer Ralph Ferrara, and at least one candidate who used to work at a prominent Wall Street hedge fund, but whose name could not be learned.

Activist investor Carl Icahn, who has been tapped by Republican Trump to play a bigger role in his administration, has been interviewing many of the of the potential SEC candidates.

During the height of the 2008 financial crisis, Clayton worked on major deals involving big banks, including Barclays Capital's acquisition of Lehman Brothers' assets, the sale of Bear Stearns to JP Morgan Chase, and the U.S. Treasury Department's capital investment in Goldman Sachs, according to his law firm's web site.

The position of SEC chair will be very important to Wall Street investors and executives at Fortune 500 companies at a time when Trump has promised to roll back regulation in a variety of areas.

Current SEC Chair Mary Jo White is slated to depart at the end of the Obama administration. Trump is to be sworn in as president on Jan. 20.

Under White, a former federal prosecutor, the SEC's focus on enforcement increased. While some of the cases have involved big firms, the SEC has also sought to crack down on relatively minor violations, in the hopes it will deter bigger problems down the road.

Some investors have said they would like to see the chair be an expert not only in enforcement matters, but have a greater understanding of markets and trading issues as U.S. firms face greater competition for global capital.

(with additional reporting by Sarah N. Lynch in Washington; editing by Linda Stern and Grant McCool)