Vivus Inc's largest shareholder, Aspen Investment Fund said it was planning to acquire the company in a $640 million deal.
On Wednesday, in a regulatory filing Aspen said it intended to have discussions with Vivus about its strategic and operations plans, management and board among other matters.
Aspen Investment Fund has a 9.65% stake in the obesity drug maker, Vivus.
On Tuesday's close Vivus had a market value of roughly $482 million and debt of roughly $269 million.
Last year, Vivus was embroiled in a protracted proxy war with shareholder First Manhattan. The company has disappointed investors with poor sales of its diet pill Qsymia.
The analyst doubt how a probable deal would assist Vivus create a partnership with a big drug maker and Aspen's plans for boosting Qsymia sales in the 2nd half of 2014 and after.
Qsymia was launched in September 2012 but sales did not pick up because of the lack of a big partner, prior safety concerns with diet medicines and reimbursement issues.
Market value the company has dropped since then. The share, which traded at about $25 in September 2012, has lost over 80% of its value.
In July last year, First Manhattan, which has a 9.10% stake in Vivus