(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.

Futures on the Standard & Poor’s 500 Index expiring in March added less than 0.1 percent to 1,837.3 at 7:28 a.m. in New York. The S&P 500 climbed to a record last week and is poised for a 29 percent gain this year. Dow Jones Industrial Average contracts advanced 10 points, or 0.1 percent, to 16,431.

“Over the course of next year, you are still going to see pretty good returns in the equity markets,” Joseph Tanious, who helps oversee $1.5 trillion as global market strategist at JPMorgan Asset Management, said on Bloomberg Television with Trish Regan and Adam Johnson. “On the back of an improving economic backdrop, and confidence, markets move higher.”

Companies in the S&P 500 are worth $3.7 trillion more than they were 12 months ago following a year when Federal Reserve Chairman Ben S. Bernanke signaled the curtailment of Economic stimulus. The bull market, born at the depths of the credit crisis, enters its sixth year fueled by zero-percent interest rates and investor confidence.

Pending home sales, the number of contracts Americans signed to buy previously-owned homes, rose 1 percent in November, the first monthly gain since May, according to the median estimate of 26 economists surveyed by Bloomberg, before a report due at 10 a.m. in Washington.

Crocs Gains

Crocs rose 13 percent to $15.07. CEO John McCarvel will step down on April 30. The shoemaker will use the Blackstone funds to increase stock repurchases to $350 million, Niwot, Colorado-based Crocs said.

Twitter slipped 1.4 percent to $62.85 in early New York trading. The social-networking company on Dec. 27 fell the most since it debuted on the New York Stock Exchange after Macquarie Capital downgraded the shares, saying they had risen “too far, too fast.”

Ben Schachter, an analyst at Macquarie in New York, lowered his rating from neutral to underperform, the equivalent of sell. The shares had jumped 40 percent since Macquarie initiated coverage on Dec. 11, without any improvement in Twitter’s fundamentals, Schachter said in a report last week.

Myriad Genetics Inc. fell 9.9 percent to $21.75. Piper Jaffray 

Cos. lowered its price estimate for the supplier of genetic tests to $29 from $36, citing a decision by the U.S. Centers for Medicare and Medicaid Services to reduce the reimbursement rate by about 49 percent for screening devices to help predict breast cancer risk.

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