California´s largest HMO´s are getting richer even as rising medical costs strain their customers.

Financial figures filed with state regulators show the HMO´s stockpiled reserves totaling $3.1 billion as of September 30th. That´s $2.2 billion more than they need to meet standards set by the California Department of Managed Health Care.

The five HMO´s are Kaiser Foundation, Blue Cross, Health Net, Blue Shield and PacificCare.

Officials with the HMO´s say policyholders should take comfort in the healthy reserves — saying they are a sort of rainy day fund.

But critics say the large sums are a sign of runaway greed.

HMO´s have been raising their rates substantially in the last two years – citing the rising cost of health care. The trend has squeezed employers and taken an even bigger chunk out of consumers´ wallets.

But many doctors believe HMO prosperity is coming at their expense and the large reserves have caused state regulators to say the plans can invest more in better services.