Solow had the largest individual loss from the Libor scandal in the U.S., estimated at half-a-billion dollars. After taking out a loan from Citibank to purchase the Consolidated Edison parcels along the East River to develop a seven-building, $4 billion project, Solow put more than $450 million in high-grade municipal bonds as collateral. However, during the economic downturn of 2008, Citi artificially inflated the Libor rates, which sank the value of Solow's bond portfolio. On a technicality, Solow defaulted on his loan, which allowed Citi to seize and sell Solow's bonds and sue Solow for the value gap of $100 million, a case Citi Bank won. In 2012, Solow attempted to sue Citi on the basis of securities fraud, but the case was dismissed. In 2013, Solow sued again, this time over Libor. As of April 2019, the New York Federal Judge ruled in favor of Citi Bank, and the Libor lawsuit will not be revived.
Solow is an extensive collector of modernist and renaissance art. Solow owns Young Man holding a Medallion by Botticelli as well as paintings by Balthus, Henri Matisse, and Franz Kline; and sculptures by Alberto Giacometti. In February 2012, he sold a Francis Bacon painting for $33.5 million, a Joan Miró painting for $26.6 million, a Henry Moore sculpture for $30.1 million; and in February 2013, he sold an Amedeo Modigliani painting for $42.1 million. In May 2015 Solow sold Giacometti's 1947 sculpture L'homme au doigt for $126.1 million, setting a world record for the most expensive sculpture ever sold. Though Solow derives significant tax benefit from the collection's 501(c)3 non-profit status, he provides no public access. In 2018, Solow arranged for his son to lead the Solow Art and Architecture Foundation, effectively passing control of the collection from Sheldon to Stefan without any estate tax.