The HouseOfTrade does not actually exists - but it is being built. As a result of the machinations of the various procurators and MerchantHouses, along with Velve, Xora, and Xarnetan and partially as an outgrowth of the HellfireClub.
Taking over the ruins of the old 7:th house compound, the merchants plan to present the GrandTemple with a fait accompli - when they requist recognition, they will already be a power to be reconed with.