As recently as a year ago, Capitolis seemed to be on to something big—big enough to change the way banks finance their hedge fund clients.

The New York-based fintech’s Ionic Capital Trust program connects money market investors in search of higher yields with banks that need financing for their equity swap activities. Instead of buying shares to hedge their client exposures, banks can enter an offsetting total return swap (TRS) with Capitolis’s special-purpose vehicles (SPVs), which issue