Snap tumbles, drags social media giants on Apple privacy tweak worries

Shares of Snap Inc plunged on Friday, dragging down other ad-dependent tech firms, after the photo messaging app owner warned of a prolonged hit from Apple Inc's privacy changes on iOS devices.

Snap shares were down nearly 20% at $60.8 before the bell, on track to open at a near three-month low. Shares of Facebook , Google parent Alphabet Inc and Twitter were down between 2% and 4%.

Apple's privacy updates, which were rolled out in June and July, prevent advertisers from tracking iPhone users without their consent. As a result, advertisers ended up spending much less than expected as the tweaks