There's a steady stream of forecasts for the online advertising industry, and despite a worrisome economic outlook, most say that digital will continue to grow at a rapid pace. But one firm that tracks such things is bucking the trend.

In a report issued late yesterday, eMarketer downgraded its estimate for this year's total online ad spend by about $1 billion dollars.

The firm had estimated total online ad spend in the U.S. to reach $25.9 billion back in March of this year, but it's now revising that figure down to $24.9 billion. However, eMarketer still expects "rapid" growth in online spending. The report, which was written by eMarketer analyst David Hallerman, cited the difficulties presented by an economic downturn.