Check out the companies making the biggest moves premarket: Regeneron Pharmaceuticals — The drugmaker fell more than 11% after its treatment for a skin cancer missed goals in a late-stage trial. Macy’s — The department store shares jumped nearly 4% in premarket after a regulatory filing revealed Berkshire Hathaway initiated a small position in the company, valued at roughly $55 million at the end of the first quarter. The stake is very small for the conglomerate, so many speculated it was bought by investment lieutenant Ted Weschler, who manages 6% of the equity portfolio. Dominion Energy — Shares popped more than 12% after NextEra Energy announced a deal to acquire the company in an all-stock transaction. NextEra said the combination of the two companies will create the world’s largest regulated electric utility business. Bio Rad Laboratories — The stock jumped 13% following a Wall Street Journal report that activist Elliott Investment Management has built a sizable stake in the company. However, the exact size of the stake nor Elliott’s vision for the company were not detailed in the report. Arm Holdings — Shares were down 1% after a Bloomberg report Friday that a probe by the U.S. Federal Trade Commission is investigating if the company is illegally monopolizing parts of the chip market. Delta Air Lines — Shares were up more than 1% after a regulatory filing showed Berkshir …
