STORY: Stocks closed mostly lower Monday with the Dow eking out a slight gain, the S&P 500 dropping half of one percent, and the Nasdaq ending the session down one-point-two percent.Investors worried about demand for technology supporting artificial intelligence while they waited for results from market heavyweight Nvidia due out Wednesday. Shares of the chipmaker ended 3% lower.Investor concerns remain over hefty spending on the technology since low-cost AI models from China’s DeepSeek rattled the industry in January.Shares of AI chipmaker Broadcom also fell sharply on Monday, while another popular AI stock, Palantir Technologies, was the tech sector’s biggest percentage decliner.Meanwhile, concerns remain about tariffs and inflation, as well as economic growth after last week’s batch of weak economic data and a disappointing forecast from Walmart.F/m investments Senior Portfolio Manager Don Nesbitt has one word to sum it all up.“I think the underlying theme is uncertainty, right? You know we’ve we’ve got uncertainty out of Washington. We have uncertainty about the state of the consumer and the market’s been trading at very high valuation, you know? So when you when you got this combination of high valuation and uncertainty. Investors get a little bit skittish, so you’ve seen that kind of the pullbacks here.”Other stocks on the move included Warren Buffet’s Berkshire Hathaway which rose 4% and hit an all-time high during the trading session after posting its highest-ever quarterly profit, driven by improvement in insurance operations.And shares of Nike climbed 5% after Jefferies raised its rating for the stock to “buy” from “hold.”