State Street Corp. said it’s becoming less likely that its purchase of Brown Brothers Harriman’s investor services unit will go through.

After bargaining for a lower purchase price and proposing changes to plans for operations and legal structure, State Street said in its earnings release Tuesday that the deal may not succeed after all.

“While discussions with regulators on the proposed modified transaction are ongoing, the likelihood of a successful outcome is increasingly uncertain,” State Street said in the statement, adding that the regulatory environment is challenging.

State Street announced plans to acquire the Brown Brothers Harriman division more than a year ago. The deal would have added trillions to the assets State Street safeguards. But fissures began to emerge earlier this year, when the Boston-based custody bank announced in July that it was renegotiating the tie-up.

This article was provided by Bloomberg News.