S&P futures were unchanged with Nasdaq futures rising 0.1% to start a traditionally brutal month for markets. 

The stock rally to all-time highs faces a crucial stretch, with jobs numbers, inflation data and the Fed's rate call all landing within the next three weeks, while September is notorious for hosting some of the worst market selloffs. The flurry of events will help determine whether stocks can extend gains or lose momentum.

Tariff tensions and questions over the Fed's independence are compounding the risks.

"The bar to derail a Fed Rate cut on Sept. 17 appears high," Deutsche Bank AG economist Peter Sidorov wrote. "But with Fed funds futures now pricing over 140 basis points of easing by the end of 2026, markets are expecting an amount of easing that since the 1980s has only occurred around recessions."

Europe's Stoxx 600 edged 0.1% higher with BAE Systems and Rheinmetall AG leading the advances in defense shares after the Financial Times reported that Europe is working on detailed plans for potential post-conflict deployments in Ukraine. Novo Nordisk lead a rally in health care shares after positive results from a real-world cardiovascular study for Wegovy. A regional gauge for tech stocks eked out a small gain. Here are some of the biggest movers on Monday:

Rolls Royce shares climb as much as 2.4% amid reports it has held exploratory talks with advisers over funding options for its small-scale nuclear reactor unit.

European defense stocks, including BAE Systems and Rheinmetall, gained after the Financial Times reported that European capitals are working on "pretty precise plans" for potential military deployments to Ukraine as part of post-conflict security guarantees, citing an interview with Ursula von der Leyen.

Novo Nordisk shares rise as much as 3.6% after the Danish drugmaker said a real-world study of people with overweight or obesity and established cardiovascular disease showed Wegovy cut the risk of heart attack, stroke or death by 57% compared with Eli Lilly's tirzepatide.