Alexander Forbes Professions (AFP) is coming under mounting pressure from rival brokers following the resignation of 26 staff from the company last week.
Market sources said that other brokers were looking to capitalise on the resignations in a bid to poach AFP's clients.
Directors Colin Taylor and Martin Ellis, along with divisional director Brian Balkin and Pat Boreham, head of AFP's broking division, are understood to be among those who have resigned.
It is thought a number have gone to Primary Group's new division Prime Professions.
"This is a major problem for AFP," one source said. "A lot of clients want first hand attention and if their main point of contact has resigned they could easily lose custom."
Another source added that AFP had been "seriously wounded", saying:
"They were a very confident team, and rivals battled with them day-to-day. By resigning they have taken the heart out of the unit."
But despite the bullish tones of rivals, it is understood that AFP is yet to lose any clients as a result of the departures.
Sources close to the company said there had been "no particular issues" at the end of its solicitors' professional indemnity renewal season on Monday.
AFP chief executive Stuart McCulloch said: "AFP maintains a well qualified staff of 160. We see this as a fantastic opportunity for the company to move forward."
' Edward Donne has joined HSBC Insurance Brokers as divisional director within its professional indemnity practice. Donne was previously client services manager at Alexander Forbes Professions.