The S&P 500 was on track for its biggest gain of the year, while shares of smaller companies surged.

A series of data reports and actions by policymakers have led investors to reassess their assumptions about interest rates and the economy.

A routine announcement by the Treasury Department about its borrowing plans has attracted more attention than usual because of the rapid rise in interest rates.

The rapid rise in interest rates in recent months has shaken investors and cast a cloud over the economy.

The 10-year U.S. Treasury yield has threatened to break above 5 percent for the first time in 16 years, rattling the markets.

Investors doubt that central bankers will lift borrowing costs again following big market moves that are widely expected to cool growth.

The report for September showed surprising strength in the economy, but that strength has become a cause for concern among investors.

A series of potential problems, including rising oil prices and labor strikes, have prompted a much warier mood among investors.

The Federal Reserve’s message of higher rates for a longer period of time has led investors to question their assumptions.

The rush by companies to borrow comes as fears of a potential recession recede and executives expect interest rates to remain high.