NEW YORK (AP) — Herbalife says that it was in talks to be acquired and taken private, but that those negotiations ended last week.

The nutritional supplement company said Monday that in response to those talks, it is selling $600 million worth of its shares to existing investors in an auction. Herbalife, which has its U.S. headquarters in Los Angeles, says it wants to give shareholders a chance to buy more stock in case the company is taken private within two years. The maneuver, known as a modified Dutch auction, will allow shareholders to pay between $60 per share and $68 per share. The offer ends next month.

Shares of Herbalife Ltd. are up 8 before the opening bell.