Wall Street looked set for a lower open on Monday, with investors cautious after Friday's rally, and global markets rattled by Hong Kong's worst protests in decades.
Volume rose and futures fell to session lows of about 1 percent in the last half hour before the open.
Futures were little changed after reports that personal income rose 0.3 percent in August, as expected.
U.S. stocks rose sharply on Friday, cutting losses for the week, after the government raised its estimate of economic growth in the second quarter and consumer sentiment rose in September.
The rally boosted Europe and other stock markets, but sentiment was hit after pro-democracy protest in Hong Kong intensified over the weekend. Riot police fired rounds of tear gas and demonstrators continued to block roads on Monday, leading schools and banks to close.
"U.S. stocks look like following Asian markets lower today, where protests in Hong Kong are bringing back memories of Tiananmen Square," said Jasper Lawler, market analyst at CMC Markets.
Hong Kong's benchmark Hang Seng Index lost 2 percent on Monday, falling to its lowest level since July.