Jefferies is also linked to Lending Club, the peer-to-peer lender that has been in turmoil since an internal investigation revealed improprieties in the sale of loans and a separate disclosure issue, which resulted in the ouster of its chief executive in May. About $22 million in loans sold to Jefferies did not meet the investment bank’s criteria, and the company bought them back.

But Jefferies did end up leading a deal that packaged Lending Club loans for investors. On Monday, Lending Club announced that the near-prime $134 million deal had three times as much investor demand as needed. This heavy interest came about even though the entire marketplace lending sector has also been hit with turbulence this year as rates for new loans rose to reflect rising delinquencies.

Leucadia’s other non-Jefferies-related assets remain a grab bag, including an Italian broadband company, a plastic net maker, auto dealers, timber and real estate. And the jury is out on more than $500 million in postmerger investments in energy and gold mining, and another $500 million in hedge funds.

Mr. Kotowski of Oppenheimer is bullish, but some investors shun the stock. Ted Hart, who follows financial stocks at Tufton Capital Management in Baltimore, said the new Leucadia with Jefferies as its core was highly correlated with the high-yield debt market. In its former life as a multi-industry conglomerate, “If one business wasn’t doing well, you had another that was picking up the slack,” Mr. Hart said.

But now, he added: “The outlook for Leucadia is kind of the outlook for the high-yield market, which isn’t too rosy. With oil prices remaining low, Leucadia may continue to struggle in high-yield debt underwriting and trading. It looks cheap on a price-to-book-value basis, but it’s an entirely different company.”

Jefferies stock swooned in late 2011 after the collapse of the commodities broker MF Global raised some concerns about its exposure to European debt, which it quickly got off its balance sheet. MF Global’s fate had raised similar questions about investor exposure at Jefferies’s commodity business, Bache.

The son of a tax preparer from Fair Lawn, N.J., Mr. Handler, 55, sold vacuum cleaners door-to-door and life insurance at a bank before graduating from the University of Rochester. After a stint as a junior analyst at First Boston during its Wasserstein Perella mid-1980s heyday, he got an M.B.A. from Stanford and worked in the Los Angeles office of Drexel Burnham Lambert before that firm’s demise in 1990. He built the Jefferies junk-bond desk before he became chief executive.