Shares of GameStop Corp. /zigman2/quotes/203755179/composite GME +0.06% soared 31.8% in morning trading Friday, but have suffered a big loss on the week, the first since the trading frenzy in the heavily shorted videogame and consumer electronics retailer started about a month ago. The has plunged 78.3% this week, after skyrocketing 1,737.2% over the previous three weeks. The stock has now shed 79.7% since closing at a record $347.51 on Jan. 27. Meanwhile, shares of AMC Entertainment Holdings Inc. /zigman2/quotes/200235402/composite AMC +5.67% , which were also caught up in the apparent short squeeze, bounced 3.1% on Friday after tumbling 21.0% on Thursday. The movie theater chain's stock, which was headed for a 44.9% loss this week after soaring 277.8% the previous week, was now trading 63.3% below the Jan. 27 close of $19.90, which was the highest closing price since October 2018. Over the past three months, GameStop shares have rallied 515.7% and AMC's stock has gained 197.1%, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.74% has tacked on 10.7%.