Consumer signups for Obamacare insurance plans topped 600,000 in the first week of the 2018 open enrollment period, offering a positive sign for insurers uncertain whether Republicans will dismantle the setup.

The Department of Health and Human Services' Centers for Medicare & Medicaid Services said that from Nov. 1 through Nov. 4, a total of 601,642 people selected plans in 39 states that use the federal website HealthCare.gov. Of those, 137,322 -- more than one in five -- were new customers.

During the first week of open enrollment for 2018, more than 200,000 consumers selected plans on the first day, which is more than double the number who signed up on the first day last year, according to a report in the Washington Post that cited unnamed federal officials.

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Despite what appeared to be good news for insurers in uncertain times, a number of major healthcare stocks pushed lower Thursday.

Anthem Inc. (ANTM) - Get Report dipped 0.82% to $215.10 in late-afternoon trading Thursday. Aetna Inc. (AET) dropped 1.8% top $172.33. Centene Corp. (CNC) - Get Report dropped 0.57% to $92.62 and Molina Healthcare Inc. (MOH) - Get Report dropped 0.1% to $76.51. The Healthcare SPDR ETF (XLV) - Get Report slid 0.18% to $81.57.

Outlier HCA Healthcare Inc. (HCA) - Get Report gained 0.42% to $79.20.

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