Warren Urges Fed’s Cook to Turn on Key Big-Bank Capital Buffer

US Senator Elizabeth Warren urged Federal Reserve Governor Lisa Cook in a letter to activate what’s known as the countercyclical capital buffer, a tool that Congress authorized the Fed to use as a way to demand banks build up additional cushions of capital during periods of excessive growth.

Warren wrote to Cook, who serves as chair of the Fed’s Committee on Financial Stability and often votes in line with Democrats, to warn about how she said President Donald Trump’s “chaotic tariff policies” might cripple the US banking system and larger economy.

The veteran Democratic lawmaker from Massachusetts ...