The biggest insurers in the health insurance marketplace raised premiums an average of 75 percent more this year than smaller insurers in each state, according to a study in the Harvard Journal of Technology Science.
The authors studied insurance plans on 34 state exchanges for pricing changes from 2014 to 2015.
The largest insurance issuers raised rates by an average of 23.9 percent, while other, smaller issuers raised rates by an average of 13.7 percent. The biggest insurers did not appear to be paying for higher medical costs per premium dollar.
"This paper provides evidence that ... the largest on-exchange insurers may be in a better position to practice anti-competitive pricing compared to their same-state counterparts," said the study's authors.