Swiss bank UBS Group is in urgent talks to buy Credit Suisse as authorities try to avoid disruptions when global markets reopen on Monday morning.
UPS reportedly offered to pay up to a billion dollars.
Meanwhile, two sources familiar with the matter said on Sunday that Swiss authorities are considering charging Credit Suisse bondholders losses as part of a bailout package, while regulators in Europe fear such a move could affect investor confidence elsewhere in the European financial sector.
Authorities are racing to save the 167-year-old bank, one of the world's largest wealth managers.
As one of the world's top 30 most regulated banks, any deal involving Credit Suisse will affect global financial markets.
Credit Suisse rejects offer
Bloomberg News, citing sources familiar with the matter, said Credit Suisse rejected an offer of up to a billion dollars because it was too low, and would hurt shareholders and employees of deferred shareholders.
If the acquisition collapses, Switzerland is considering acquiring the entire bank or owning a large stake in the shares, Bloomberg reports.
Britain's Financial Times reported that a deal to acquire all the shares was due to be signed early on Sunday.
It quoted sources familiar with the matter as saying that the offer made today was 0.25 Swiss francs ($0.27) per share, which is much lower than the share price of Credit Suisse at the close on Friday, when it reached 1.86 Swiss francs.
A source familiar with the matter told Reuters earlier that UBS had asked the Swiss government for $6 billion as part of a potential deal to buy Credit Suisse, covering the cost of liquidating parts of the bank and possible litigation fees.
Credit Suisse is in the process of cutting 9,<> jobs in a bid to save itself, even before it is forced to enter into crisis negotiations on Sunday.
Bloomberg news agency reported on Sunday, citing sources familiar with the negotiations, that number of jobs is just the beginning if the bank is to be pushed into a takeover by UBS, while one source estimated that the final outcome of job write-offs could be many times that figure.
The two banks together employed about 125,30 people at the end of last year, with <> percent employed in Switzerland.