NEW YORK—With the mortgage market reeling from massive loan defaults, analysts are now predicting disaster for the banner ad industry.

"Those eye-catching dancing motions on our nation's web pages are in dire jeopardy," said editor Brian Weingrad of the industry trade publication Banner AdWeek on Monday. "The reassuring sight of a smiling African-American woman jumping up and down and screaming with excitement could soon be a thing of the past."

The collapse is considered the worst crisis in online business since the Great Flash Animation Shortage of 2003 nearly wiped out that year's pop-up crop.