Fiat has declined to comment on the situation, but GM Vice Chairman Stephen Grisky said in a statement that GM stands behind Opel and that the brand is "a fully integrated part of GM's global footprint."
Grisky also said the GM-PSA alliance is still strong.
This isn't the first time rumors have swirled around Fiat's lust for Opel. The Italian brand attempted to buy Opel once before in 2009 when GM was briefly in bankruptcy. The American manufacturer eventually settled on keeping Opel, however. Meanwhile, Marchionne has said the European auto industry will have to consolidate if it is to survive the region's economic downturn.