Before the bell rings, here’s a look at companies in the spotlight: United States Steel — The industrial stock plunged 6% after Vice President Kamala Harris spoke out against the proposed sale of United States Steel to Japan’s Nippon Steel Corporation. At a Labor Day rally in Pittsburgh, Pennsylvania, before union members, Harris said United States Steel is “a historic American company, and maintaining a strong American steel company is critical to our country.” Boeing — Shares fell 3% after Wells Fargo downgraded the aircraft maker to underweight from equal weight. Analyst Matthew Akers cited the company’s peaking free cash flow as the reason for the downgrade. Unity Software — Shares of the video game maker rose 6% after Morgan Stanley upgraded Unity’s shares to overweight from equal weight. Morgan Stanley cited Unity’s status as a “clear game engine” and de-risking future prospects as factors driving the stock’s rise. NetApp — The data storage stock rose 1.6% after Loop Capital upgraded it to buy from hold. Loop analyst Ananda Baruah cited several factors, including NetApp’s cloud storage software partnerships and the recent share price decline. Novartis — Novartis shares fell 1.7% after Jefferies downgraded the stock to hold from buy. Analyst Peter Welford said he was optimistic about the drugmaker’s long-term trajectory but noted Novartis will need until 2025 to get more approvals. Bank of America — The bank’s shares fell slightly. Warren Buffett’s Berkshire Hathaway began trimming its holdings in Bank of America this summer, but said on Friday it sold more shares last week. Merck — The pharmaceutical giant announced Tuesday that the European Commission has approved a drug combination that includes Merck’s Keytruda to treat bladder cancer. Merck shares were little changed. — CNBC’s Michelle Fox and Jesse Pound report.