Jerome Powell, chairman of the US Federal Reserve, waited until Representative Carolyn Maloney, a Democrat from New York, asked him about the number of likely interest-rate increases during 2018 to take the opportunity to hint that four increases of 25 basis points each were likely because of a strengthening US economy, rather than the consensus estimate of three. That pushed the 10-year yield up by 5 basis points and erased about a third of Tuesday’s gain in the US stock market.