Microsoft reported earnings last night, and in after-hours trading, it seems, for the most part, that Wall Street is happy. But if you look at the search ad revenue numbers, that department’s growth continues to slow.

The earnings report wrote, “Search and news advertising revenue excluding traffic acquisition costs increased 10% (up 15% in constant currency).”

So that is great, the ad revenues from Bing Search and news ads were up 10% and hey, if you use “constant currency,” exchange rates used to eliminate the effect of fluctuations when calculating financial performance numbers for publication in financial statements, then it was up 15%.

But if you look at the previous quarters, last quarter search ads for Microsoft was up 16%, the quarter before that was up 22% each, and the quarter before that, they were both up about 32% each.

Here is a chart showing the growth decline – if I did it correctly:

Google doesn’t report earnings until the end of next week but I suspect they won’t be looking much better.

Forum discussion at Twitter and WebmasterWorld.