Stocks fluctuated as a post-earnings rally in Twitter (TWTR) - Get Report shares faded. Defensive stocks in the utilities and basic materials sectors were also a drag following an increase in 10-year Treasury yields. Strong demand in the U.S. housing sector boosted pending home sales to a higher level than expected in September. Activity in the Western and Southern markets boosted the bulk of growth last month. Potash (POT) reported double digit percentage declines in profit and sales over its recent quarter as the price of fertilizer nutrients continued to decline. Net income fell 71%, while sales dropped 26%. Groupon (GRPN) - Get Report agreed to purchase LivingSocial, one of its big competitors in the online discounts market. Groupon did not disclose the price it paid, but said the cost was not material. The purchase is expected to add 1 million active customers.