By Carl O'Donnell and Svea Herbst-Bayliss (Reuters) - Hedge funds Corvex Management LP and Sachem Head Capital Management LP have built stakes in U.S. health insurer Centene Corp and are exploring challenging its planned $17.3 billion acquisition of WellCare Health Plans Inc, people familiar with the matter said on Monday. The hedge funds believe that Centene may be able to do more to establish if another company such as Humana Inc would be interested in acquiring it, the sources said. The post Exclusive: Hedge funds target Centene, may oppose WellCare deal-sources appeared first on Firstpost.