Damage estimates for the powerful tornado that struck Moore, Oklahoma last week are increasing with disaster modelling firm Risk Management Solutions Inc now saying the twister may have caused as much as $3.5 billion in insured losses.The firm says the massive EF-5 tornado damaged as many 20,000 buildings and completely destroyed between 4,000 and 5,000. About 95 percent of the affected buildings are residential structures, said Matthew Nielsen, director of model product management at RMS.The estimate includes the heavily impacted community of Newcastle, Oklahoma and incorporates damages to personal, commercial and industrial structure, adding together predicted losses from property, contents and business interruption.The estimate does not include damages to vehicles.RMS’s estimate of insured losses, ranging from $2 billion to $3.5 billion, is the latest sign that last week's deadly storms won't take a massive bite out of insurer profits. The Moore tornado appears on pace to become the most expensive tornado in US history, but the cost to the insurance industry looks to be industry significantly less than last year's superstorm Sandy or a string of tornadoes that struck a number of states in 2011.The Joplin tornado of 2011 resulted in insured losses of about $2.4 billion.Damage estimates from RMS and other disaster-modelling companies are closely tracked by the insurance industry for the early indication they can provide about the financial impact of major catastrophes.Catastrophe modellers produce their estimates by evaluating data about insured property in the affected areas and examining the damage on the ground.A rival firm, Eqecat, on Friday said the Moore tornado and other storms that hit over a three-day stretch last week likely combined to cause between $2 billion to $5 billion in insured losses.The estimates aren't directly comparable. While Eqecat said the bulk of its damage estimate was from the Moore tornado, it also included storm damage from several other states, including Kansas, Illinois, Colorado, and Texas. And Eqecat included the claims costs that car insurers could incur, while RMS excluded it.State Farm Mutual Automobile Insurance Co is the largest property insurer in Oklahoma, with a 17 percent market share. Farmers Insurance is second and Liberty Mutual is third, according to data provider SNL Financial. The largest publicly traded insurer in the state is Allstate Corp, ranked fifth, with a 4.5 percent market share.