The rating agency said a 3% minimum leverage ratio under new regulations was credit positive for Mexico's commercial banks.
The central bank sees the open banking model as a way to boost competition, reports local daily Valor.
Polls continue to show the ultra-rightwing candidate enjoying a significant lead over leftist Fernando Haddad.
Faced with a possible merger with fellow development bank Nafin under the next administration, Bancomext chief Francisco González Díaz said improving efficiency was central to discussions with the incoming government.
The UN's anti-corruption commission confirmed that the Guatemalan government has revoked courtesy visas and denied future visas for CICIG members and associates.
A central bank estimate shows that pre-tax income grew almost fourfold year-on-year in August.