Nuclear stocks plunge as regulator blocks data center deal

Major U.S. stock indexes fell on Tuesday, the last market session before Election Day. Beyond key policy developments, the trading week will include Thursday's Federal Reserve interest rate announcement and the latest corporate earnings reports.

The S&P 500 closed 0.3% lower as voters prepared for the election. The Nasdaq also fell 0.3%, while the Dow lost 0.6%.

Shares of power producer Constellation Energy (CEG) fell 12.5%, the most of any S&P 500 stock, as a Federal Energy Regulatory Commission decision raised questions about the nuclear power industry. The regulator reportedly rejected a deal between Amazon (AMZN) and nuclear power plant Talen (TLN), citing potential negative impacts for nearby customers if Talen uses additional energy from its nuclear facility to power the e-commerce and data center cloud computing giants would spend. Similar regulatory scrutiny could fall on a deal signed last month by Constellation Energy that would see the company restart a shuttered nuclear power plant in Pennsylvania to power Microsoft's (MSFT) data centers.

The headwinds for nuclear power plants also weighed on shares of New Jersey-based utility Public Service Enterprise Group (PEG), which fell 6.2%. Adding to industry pressures, the company reported mixed third-quarter results that fell short of profit expectations but beat revenue forecasts. Although the company benefited from higher energy margins and tax credits, it now expects to exceed its original full-year capital plan.

Shares of United Airlines (UAL) fell 4.0%, erasing some of the airline's strong October gains. While optimism about the airline industry focused on well-timed capacity reductions over the summer, a rise in crude oil futures prices on Monday and the prospect of higher fuel costs may have contributed to pressure on United shares.

Shares of fertilizer giant “Mosaic” (MOS) rose 5.4% on Monday, the best daily performance in the S&P 500, after reports that Belarusian President Alexander Lukashenko had proposed cutting potash production to boost prices for the to boost the most important plant nutrient. Any price improvement would be welcome news for Mosaic, which has warned that operational issues could limit potash production and supply volumes this quarter.

Shares of Sherwin-Williams (SHW) rose 4.6% after news that the paint maker's shares will be added to the Dow Jones Industrial Average (DJIA), surpassing chemical giant Dow Inc. (DOW) in the price-weighted index 30 Blue Indices Replace. Chip company, valid before trading begins on Friday. S&P Dow Jones Indices also announced that AI chip giant Nvidia (NVDA) will replace Intel (INTC) at the DJIA. Inclusion in such a widely followed index can boost stock prices as index-tracking funds buy shares.