Documents from GM's bankruptcy filing on Monday show the car giant owes Publicis media agency Starcom MediaVest $121m and the holding company itself $25m.
However, Publicis says the principle of sequential liability that applies media agency deals means its exposure is lower.
While Starcom MediaVest may owe $121m to media owners for the purchase of space for GM, it is only liable for the payment of invoices to the extent that it has been paid for GM.
In addition, Publicis says things could turn out even better depending on the turn that GM's bankruptcy proceedings take.
GM has asked the bankruptcy court to grant "essential vendor" status to Publicis Groupe agencies and it expects to pay them and work with them when it emerges from bankruptcy as a new company.
Publicis said: "In the event our agencies either are deemed essential or have their contracts assumed if the GM sale is approved, our agencies will have an important protection that reduces their exposure to the risk of non-payment of their debts in connection with GM before the date of the petition for protection, and assures a good relationship with the new company."
Despite the assurances Publicis was hit yesterday by an update from rating agency Standard & Poor's, which put its credit ratings on watch for downgrade.
S&P said there were risks to Publicis' BBB+ long-term corporate credit and senior unsecured debt ratings such as GM deciding to end its contract, Publicis' financial exposure through media deals and possible losses on other outstanding receivables from GM.