Starting in 2014, the Affordable Care Act transformed the market for individual health insurance by changing how insurance is sold and by subsidizing coverage for millions of new purchasers. Insurers, who had no previous experience under these market conditions, competed actively but faced uncertainty in how to price their products. This issue brief uses newly available data to understand how health insurers fared financially during the ACA's first year of full reforms. Overall, health insurers' financial performance began to show some strain in 2014, but the ACA's reinsurance program substantially buffered the negative effects for most insurers. Although a quarter of insurers did substantially worse than others, experience under the new market rules could improve the accuracy of pricing decisions in subsequent years.