MILAN, (Reuters) – Credit Suisse shares tumbled on Thursday as investors grew skeptical about a potential takeover by U.S. financial giants. State Street (NYSE:) After a Wednesday media report lifted the stock’s heavily-shorted level from near 20-years lows,

State Street stated that overnight, in response to an Inside Paradeplatz report suggesting that the U.S.-based group planned a takeover offer, it was focusing its attention on Brown Brothers Harriman’s Investors Services.

Credit Suisse shares fell further from Wednesday’s highs due to a lack of confirmation. They had fallen 3.5% by 0708 GMT, and were below the European broader market that was 0.5% lower before a European Central Bank policy conference.

Analysts consider any potential takeover highly unlikely due to limited synergies, as well as a variety of risks, including capital costs and litigation. State Street may be interested in the asset management industry.

Credit Suisse issued its third quarterly profit warning, prompting speculation about the deal.