Last week, UBS declared it had no interest in going through with the merger, stating, "it is not conducive to UBS's interests to pursue this proposal".
CSFB has already lost key staff in the last few weeks to UBS. CSFB executives fear the rush for the exit could turn into a stampede.
An aggressive style has been a hallmark of the firm's approach, despite the many toes trodden on in the process. "Credit Suisse is run by Swiss who think they are Americans," said one analyst.
"Happiness and CSFB are mutually exclusive concepts," he added, saying CSFB management was already worried by recent defections.
Tom Hanley, the top-rated banks analyst on Wall Street, was recently poached away by UBS for a reputed $2m (pounds 1.3m) annual salary - plus bonuses - while John Costas, head of fixed income at CSFB in the US, joined UBS there as head of global fixed income.
CSFB, 68.5 per cent owned by CS Holding, has had a troubled few years.
Many say it has lost its touch since the legendary Hans-Joerg Rudloff quit in 1994. Rudloff was widely credited with building CSFB into a powerhouse among European investment banks.
In May of last year, CSFB's highly profitable Russian operations - Rudloff's last creation at the bank - began to suffer after its chief, Boris Jordan, resigned.
Although it boasted a remarkable debt franchise, CSFB has been unable to build a strong presence in European equity distribution, the key profit centre for big investment banks in recent years.
Its parent, CS Holding, however, is too big to consider as a takeover candidate. Nor is there much chance of a hostile bid by CS Holding for UBS, to create a bank valued at pounds 27bn, and the world's second largest after Bank of Tokyo-Mitsubishi Bank of Japan, by assets.
The abortive merger plan had already sparked outrage among many Swiss trade union leaders and politicians. It could have led to 15,000 job losses out of a combined workforce of 40,000.