NEW YORK :Envestnet, a U.S. software vendor with a market value of about $3.5 billion, is exploring options that could include a potential sale after receiving takeover interest, people familiar with the matter said on Tuesday. Berwyn, Pennsylvania-based Envestnet is working with investment bank Morgan Stanley to engage with potential acquirers, the sources said, requesting anonymity as the discussions are confidential. Private equity firms, including Bain Capital, are among the parties that have expressed interest in acquiring Envestnet, the sources added, cautioning that no deal is certain.