"This short-term financing will remain until it is replaced by the proceeds of a convertible bond to be issued by GAM in an amount of about CHF 25 million," the Swiss fund manager said in a statement.
GAM said shareholders will get to vote on this at the next extraordinary general meeting (EGM), to take place on or around September 27.
Last week a takeover offer from Liontrust won the backing of just 33.64% of GAM's shareholders. On Tuesday the British firm formally declared its bid unsuccessful.
Liontrust offered 107 million Swiss francs in its own shares at the time, a deal now worth considerably less owing to a decline in Liontrust's share price.
The investor group with ties to Neil had vehemently opposed the all-share offer, saying in July that it "grossly undervalues GAM" and instead wanted to keep GAM listed, restructure it and focus more on business with super-rich private clients.
The investor group will propose new GAM board members at the upcoming EGM, where the fund manager's current board is expected to stand down.
($1 = 0.8833 Swiss francs)
(Reporting by Noele Illien, editing by Friederike Heine and Jason Neely)
