* Cites reports of trading glitches, oral disclosures

* Says it followed customary practice

* Market value has fallen by a quarter since trade debut (Recasts, adds comments from motion)

By Basil Katz and Edwin Chan

NEW YORK/SAN FRANCISCO, June 15 (Reuters) - Facebook Inc , facing a raft of lawsuits from investors seeking to recoup losses from its botched IPO, laid out on Friday how cascading Nasdaq trading glitches might have contributed to the confusion surrounding its May 18 debut.

The No. 1 social network and lead underwriters Morgan Stanley, Goldman Sachs Group Inc and JPMorgan Chase & Co filed a motion requesting that dozens of shareholder lawsuits over its $16 billion initial public offering be grouped together in Manhattan federal court.

The filing, while standard in cases with multiple lawsuits, hints at how Facebook may choose to structure its defense.

Nasdaq spokesman Joseph Christinat declined to comment.

More than a dozen shareholder lawsuits have accused Facebook and its underwriters of hiding the company's weakened growth forecasts ahead of the May 18 stock offering, one of the largest IPOs in U.S. history.

Nasdaq OMX Group Inc has also been sued by investors who claimed the exchange operator was negligent in handling orders for Facebook shares.

Facebook's IPO was to have been the culmination of years of breakneck growth for a social network that became a cultural and business phenomenon. But shares in the eight-year-old company founded by Mark Zuckerberg in his Harvard dorm room have shed almost a quarter of their value, or $24 billion, since their debut at $38 a share.

In the motion filed late Thursday, Facebook - which was the first American company to debut with a market value of more than $100 billion - defended its pre-IPO disclosures on mobile user revenue growth. The motion cited reports that Facebook had told underwriters about lowered revenue forecasts but not amended its prospectus.

Plaintiffs "ignore that what Facebook and the underwriter defendants allegedly did both followed customary practices and did not violate any rules," according to the motion.

Facebook also cited a series of press reports which described how trading errors compounded uncertainty on May 18, after commencement of trading in its shares was delayed by about half an hour.

The motion cited lawsuits "alleging that technical problems and other trading-related errors affecting Facebook's stock - which Nasdaq has subsequently admitted - created market uncertainty and caused investor losses."

In court papers filed late on Thursday before the U.S. Judicial Panel on Multi-District Litigation, Facebook and the banks said the U.S. District Court in Manhattan was the "most appropriate and convenient forum to oversee these coordinated and/or consolidated proceedings."

In afternoon trading on Friday, the stock was up 2.2 percent at $28.91. (Editing by Bernadette Baum)