Wall Street’s commitment to buy back auction-rate securities grew to more than $41bn on Friday when UBS reached an agreement with financial regulators to repurchase $18.6bn of such debt instruments.

Regulators have accused banks of misrepresenting ARS as liquid, cash-like instruments. The collapse of the $330bn market in February underscored the risk in the long-term securities, whose interest rates are periodically reset at auctions.