U.S. stock futures are signaling a lower opening Monday on Wall Street as markets around the globe fell, pausing from a recent surge.

An Oppenheimer and Co. analyst downgraded shares of Genzyme Corp. Monday, pointing to the biotechnology company’s manufacturing problems and changes in Medicare payments that could hurt sales.

S&P 500 stock index futures sank further on Monday and global equity markets declined as investors reassessed stock valuations following a six-month run-up.

The relatively lackluster performance of Alliant Techsystems Inc. belies the military contractor’s potential and reflects investors’ anxiety about NASA’s plans for the Ares rocket program on which Alliant works, an analyst said Monday.

Analysts raised their earnings estimates on Cooper Tire & Rubber Co., saying the tire maker stands to benefit from proposed tariffs on Chinese tires.

Higher sales in August, upbeat comments from management and international stores were among the reasons an analyst gave Monday for upgrading shares of warehouse club operator Costco Wholesale Corp.

Cytec Industries Inc. is positioned to grow on rising demand from its coatings-resins segment and long-term strength from its engineered-materials segment, said an analyst on Monday as he upgraded the specialty chemicals maker’s stock.

A Credit Suisse analyst downgraded Altria Group Inc. Monday, worried about possibly declining Marlboro prices and the company’s ability to balance profit and market share growth for the cigarette brand.

Celgene Corp. shares could stage a recovery by the end of this year due to increased use of the cancer drug Revlimid, said a Robert W. Baird analyst who upgraded the stock Monday.