Images wsjVenture-capital firms are jumping into the stock market, buying up battered shares in publicly traded tech companies at a time when they are investing less in the startups that have long been their focus.

Some major venture firms including Accel and Lightspeed Venture Partners have purchased more stocks of companies they first backed as startups this year, defying the industry norm of selling those shares soon after public listings.

Image: One of Amplitude’s largest shareholders when the data-analytics firm went public was Sequoia Capital. PHOTO: ANDREW KELLY/ASSOCIATED PRESS