(Bloomberg) — Canada’s mortgage lenders and the largest private insurer plunged amid concerns that new measures by the federal government to cool the housing market will hurt their businesses.Genworth MI Canada Inc. led the declines, with an 8.7 percent drop at the close in Toronto on Tuesday, its biggest drop since July 2009. The Toronto-based mortgage insurer said more than a third of insured mortgage borrowers would struggle to meet the new standards introduced Monday.First time homebuyers in particular “would have difficulty meeting the required debt service ratios and homebuyers would need to consider buying a lower priced property or increase the size of their down payment,” the company said Tuesday in a statement. About 50 percent to 55 percent of the company’s total portfolio of new insurance written would no longer be eligible for mortgage insurance under the new requirements, the company said.Finance Minister Bill Morneau introduced the …