US stocks set for cautious open as Federal Reserve meeting kicks off

U.S. stock index futures pointed to a mixed open on Tuesday as the Federal Reserve's open market committee meeting kicks off.

The Fed's policymaking committee is largely expected to hold rates steady this week. Market expectations for an interest rate hike on Wednesday are just 4.8 percent, according to the CME Group's FedWatch tool.

The Dow Jones and S&P 500 futures pointed lower, while the Nasdaq was called higher, after closing Monday's session at an all-time high.

On the data front, Tuesday will see U.S. auto sales figures for April. The number is expected to come in at an annual rate of 17.2 million, compared with March's annual rate of 16.6 million.

On the earnings front, major companies set to report before the bell include Apple, Mondelez and Western Union are due to report after the bell. Dow component Pfizer reported mixed results, with earnings topping expectations while sales missed. Merck, another Dow member, beat expectations on both the top and bottom lines.

In Europe, the pan-European Stoxx-600 index was around 0.4 percent higher on Tuesday. In Asia, the Shanghai Composite in China closed 0.35 percent lower, while the Nikkei in Japan closed 0.7 percent higher.

In oil markets, Brent crude traded at around $51.99 a barrel on Tuesday, up around 0.91 percent, while U.S. crude was around $49.14 a barrel, up 0.61 percent.

CNBC's Fred Imbert contributed to this report