It was broken up into "constituent" components in 1998, and the a lot of the nuclear plant construction financing debt didn't fit neatly into any one of them, so a separate legal entity was created: Ontario Electricity Financial Corporation (OEFC).
Ratepayers pay their electrical bills, the money goes to local utilities and entities like OPG and Hydro One, which in turn pay OEFC.
The claim that it was bankrupt was a line used by Mike Harris et co to justify privatization.