UPDATE 2-Olivant in touch with Lehman to secure UBS stake

(Adds more Olivant comment)

ZURICH, Oct 1 (Reuters) - Activist investor Olivant is in contact with the administrators of collapsed bank Lehman Brothers to secure its 2.78 percent stake in Swiss bank UBS (UBSN.VX), which the fund holds through Lehman.

Olivant, the investment company of former UBS Chief Executive Luqman Arnold, earlier this year clashed with UBS's new management and called for a separation of the Swiss bank's troubled investment banking business from its money-generating wealth management arm.

Olivant said in a statement the stake -- worth about $1.34 billion, according to Thomson Reuters data -- is held through Lehman Brothers International (Europe).

"We're in discussion with Lehman to establish the ownership of the shares," Arnold told the Financial Times. "We are doing everything we can to recover our position."

The announcement casts doubt on whether Olivant can vote at UBS's extraordinary shareholder meeting on Thursday, when the bank will present a restructuring plan announced in August along the lines demanded by Arnold.

The market is only just starting to understand the impact of a prime broker going bankrupt, because no one had ever considered the consequences before, Arnold told the FT.

The newspaper reported that although Olivant's stake was large, its actual exposure is significantly smaller because it had used leverage to boost its UBS investment, meaning it would remain solvent even if the entire investment was lost.

"We are fortunate that we are a private company, and a company which has substantial paid-up capital, which means that this is not a drama for us," Arnold said. (Reporting by Lisa Jucca and Sam Cage; Editing by Paul Bolding)