STORY: U.S. stocks closed lower on Monday, with the Dow losing nine-tenths of a percent, the S&P 500 shedding more than half a percent and the Nasdaq dropping over a third of a percent.High stock valuations and the future path of interest rates continue to drive market action, says Melissa Brown, managing director of investment decision research at SimCorp.“I think we've just been going back and forth between risk on days and risk off days. And it kind of suggests this underlying volatility that investors can't really make up their mind. And so they're just having a hard time. Today it's AI or today it's not AI. Tomorrow you know, it may be and or you know, it may also be, you know, the Fed and the back and forth. First of all, is the Fed going to lower rates? And second of all, if they lower rates, is that good news or bad news?"Markets have largely priced in a December rate cut from the Fed. Despite those expectations, U.S. Treasury yields were higher on Monday, pressuring stocks.Bitcoin also stumbled, at one point dropping below $85,000.Shares of Strategy, formerly known as MicroStrategy and the world's largest holder of bitcoin, ended more than 3% lower after tumbling as much as 12%. It cut its earnings forecast for 2025, citing a weak run in bitcoin.Crypto-related stocks Coinbase and Bitfarms also fell. Among other movers, Synopsys shares closed about 5% higher after AI chip leader Nvidia said it had invested $2 billion in the semiconductor design software provider.