Fears that Democratic candidate Hilary Clinton would win the election and limit gun sales led to record purchases last year, but Trump's surprise victory has had a reverse effect, with 2017 sales falling and investors selling gunmaker shares.

U.S. Federal Bureau of Investigation background checks in July fell 25% to 907,348, according to the National Shooting Sports Foundation. That was the worst year-over-year decline in background checks since November 2013, a year after Democratic President Barack Obama won his second election.

Background checks are a strong proxy for monthly gun sales, whose figures manufacturers do not publicly release.

Reflecting lower demand for guns, Sturm Ruger & Company (rgr, +1.13%) on Thursday reported revenue for the quarter ending on July 1 down 22% at $132 million. The company said the drop was due to unusually strong demand last year related to the Nov. 8 election.