An Affordable Care Act program meant to ease risks for health insurers in the law’s new marketplaces will initially pay many companies less than they expected, likely putting financial strain on some.

Federal authorities said that insurers will at first receive only about 12.6% of the money that they requested from the program, known as risk corridors, for 2014, its first year of operation. Insurers have requested approximately $2.87 billion in payments from the program based on their 2014 results. But the pool available to make those payments is just $362 million, which came from collections from other insurers that did relatively well on their marketplace business.