Bermuda-based energy industry mutual Oil Insurance Limited is to lose 13 shareholder members by the end of next month.

That will reduce the total shareholders of OIL to 61. At the end of 2006 there had been 83 members but nine others left on January 1.

Last Friday a further 12 shareholders, nine of whom are utility companies, gave notice of their withdrawal from OIL and that they would not be renewing their policies. A further shareholder is no longer eligible to be a member because of a merger with a non-OIL member.

OIL is the largest of three mutual companies making up the OIL Group of Companies.

The number "wasn't outside of our range of expectations—obviously we would prefer for it to be much smaller," said George F. Hutchings, OIL's senior vice-president and chief executive officer. "It wasn't a stunning blow to us."

Once they have withdrawn the companies will be obligated to pay to OIL the full amount of their respective withdrawal premium/avoided premium surcharges, which are estimated to total more than $100 million.

"The organisation is certainly disappointed to see any members leave, but we respect their decisions and wish them well," Mr. Stauffer said in a company statement. OIL said it "does not believe that the departure of these shareholders will have a material adverse effect on the ability of OIL to continue to provide its members with the capacity and coverage our shareholders have come to expect".

Together the 13 departing shareholders represent 9.5 percent of the gross assets of OIL although none of the departing shareholders has more than 1.9 percent of the pool's weighted gross assets, according to news reports.

A reason for the loss of the shareholders has been mooted by the company as a result of the hurricanes Katrina and Rita in 2005 causing energy price spikes for which the utility shareholder members were unable to offset with revenues.