Yahoo's prized investment in Chinese Internet company Alibaba Group has turned into a stock market millstone, according to AP. Alibaba's recently disclosed spinoff of an online payment service called Alipay is raising worries about the value of Yahoo's 43 percent stake in Alibaba. The fallout is bringing the rocky relationship between the two companies into sharper focus as they bicker over the decision to turn over Alipay to another company controlled by Alibaba CEO Jack Ma. Investors are disillusioned, partly because Yahoo waited nearly two months to announce the Alipay spin-off. Yahoo Inc.'s stock price has fallen by 10 percent in the past three days since the company disclosed the change in Alipay's ownership. That included a drop of 55 cents, to $16.62 in midday trading Friday.