Assuring Coverage for Americans with Pre-existing Conditions Act of 2009 - Requires the Secretary of Health and Human Services (HHS) to provide to each state an amount equal to 50% of the state's expenditures to provide for the use of a high-risk pool, reinsurance pool, or other risk-adjustment mechanism to subsidize the purchase of private health insurance for the high-risk population (not to exceed 50 cents multiplied by the average number of state residents in a fiscal year).