Pinterest forecast current-quarter revenue below Wall Street expectations on Tuesday as the image-sharing platform faces tough competition in a stabilizing digital advertising market, sending its shares down about 12% after hours.

The company, whose shares shed about $3 billion in value, competes with the likes of TikTok and Meta Platforms-owned Facebook and Instagram - the preferred platforms for advertisers because of their larger user base and higher engagement for targeted ads.

"After results from both PINS and GOOGL, we believe that digital ad spend remains healthy but tougher comparisons are causing trends to decelerate at a faster pace than expected. Still, we think the pullback in shares provides an enhanced opportunity," said Angelo Zino, senior equity analyst at CFRA Research.

Pinterest has also launched ad partnerships with e-commerce giant Amazon.com and Alphabet's Google, while unveiling an automated ad campaign setup tool and Pinterest Performance+, an AI-powered tool for marketers.

The company expects revenue in the range of $885 million to $900 million for the third quarter, compared with analysts' expectations of $906.6 million, according to LSEG data.

"Our revenue guidance reflects further progress against our strategic initiatives, including continued lower funnel strength and the ongoing emerging contribution from third-party demand partnerships," CFO Julia Donnelly said on an earnings call.

Revenue for the second quarter ended June 30 rose 21% to $853.7 million, higher than estimates of $847.8 million.

Pinterest's global monthly active users (MAUs) rose by 12% to 522 million in the second quarter, compared with estimates of 519.2 million.

Excluding items, Pinterest posted a profit of 29 cents per share, compared with estimates of 28 cents.

(Reporting by Juby Babu in Mexico City; Editing by Devika Syamnath)