STORY: U.S. stocks ended sharply higher on Friday, with the Dow and S&P 500 each adding about 1% and the Nasdaq gaining just under 1%.But all three indexes posted losses for the week amid concerns over lofty tech valuations.:: NvidiaThat was exacerbated by shares of Nvidia, which initially rose after the chip maker's strong earnings report on Wednesday, but led a widespread selloff a day later.Anna Rathbun, founder and CEO of Grenadilla Advisory, explains.“I think the Nvidia effect of the week was overdone. There was a lot of fear going into it, anticipation. If Nvidia was to sell, it didn't mean that we needed to sell Gap, right? So there was sort of a dump everything effect, and I think today it's turning around. But remember, there's also weakness in the economy. There's a lot of things that the market has to digest going into the end of the year. So I would sort of look at today as dip buyers coming in temporarily. But next week we'll see where the direction of the market is and whether or not that has staying power.”:: NvidiaShares of Nvidia briefly jumped in afternoon trading after sources said the Trump administration is considering green-lighting sales of the company's H200 AI chips to China. But the stock still ended down 1%.:: Eli LillyAmong other movers, shares of Eli Lilly gained one and a half percent as the company became the first drugmaker to touch a $1 trillion market capitalization.And shares of Gap rose more than 8% after beating Wall Street expectations for third-quarter sales and profit, helped by strong demand for its Old Navy and Banana Republic apparel.