The finance sector's ability to bounce back from the recession has been impaired by the scale of the job losses in the industry, according to report.
Around 20,000 jobs have been axed by finance firms since the start of the year.
This has "seriously" damaged their chances of getting back on their feet, according to Unite.
It says continued job losses would only make the situation worse.
National officer Rob MacGregor said: "Banks and insurance companies are failing to recognise the damage that will be done... if they continue to simply slash thousands of staff each month.
"Nearly 20,000 job losses in the last four months represents a significant loss in the sector.
"The financial services industry must ensure that it protects its workforce in order to stand a chance of emerging from the current crisis."
He added: "Without these highly trained and experienced people there is no chance that the UK will be able to re-build its reputation for a world class industry.
"The union wants to see companies in the financial industry consider the long-term implications of their short-term cost-saving plans."
Unite says its members should not have to pay for the mistakes made by the highly paid executives and traders who caused the economic meltdown.