(Bloomberg) -- U.S. stock-index futures were little changed, after the Standard & Poor’s 500 Index advanced for a second week, heading toward its biggest annual gain since 1997.

Crocs Inc. rose 13 percent in pre-market New York trading after saying its chief executive officer will retire and Blackstone Group LP will invest $200 million in convertible preferred stock in the maker of colorful plastic clogs. Twitter Inc. extended last week’s decline, falling 1.4 percent.

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