Rangers aim to raise £6.75m after launching a share issue for supporters, giving them the chance to "help future-proof" the club.
Pre-registration runs until 11 June, with the minimum investment £500 and the maximum £100,000.
Rangers predicted they needed £23.2m in fresh funding by the end of next term when they posted a £15.9m loss in November for the year to July 2020.
The Ibrox club won their first top-flight title in a decade this season.
Funds raised from the share issue will go towards "projects designed to accelerate the financial sustainability of Rangers," says managing director Stewart Robertson.
These include "investing in the new Edmiston House multi-purpose venue, developments at Ibrox Stadium, the acceleration of Rangers' digital transformation strategy and the club's international expansion".
Subscribers will have the same rights as current owners and shareholders, including one vote per share and the right to attend the club's annual general meeting.
Chairman Douglas Park said: "Rangers has been here for 150 years and it's vital that we future-proof the next 150 years. By widening the ownership to a broader base of like-minded supporters and shareholders, we feel it helps put the club on an even stronger footing going forward."
Sporting director Ross Wilson says it is a "wonderful opportunity" to become part of a club "heading in a positive direction".