This month’s glitch-filled rollout of the health insurance marketplaces created by federal law is a business opportunity for brokers and agents, but regulators warn that it also opened the door for those who would seek to line their pockets by misleading consumers.

New Hampshire’s insurance commissioner sent a cease-and-desist letter last week to an Arizona company he accused of building a website to mislead health care shoppers into thinking it was the official marketplace. The site was taken down Friday.

Regulators in Washington state and Pennsylvania also have told agents to change websites that seemed likely to convince consumers they were connecting to government-run sites. Connecticut’s insurance department warned agents and brokers this summer that it will take action against agents who mislead consumers or design sites to replicate the state-run exchange.