It’s not often that a single one of the cloud and SaaS providers we track can affect the overall average performance of the Talkin’ Cloud Stocks Index. But the Vocus acquisition of iContact was so poorly received by investors that the entire Talkin’ Cloud Stocks Index dipped 1.51 percent for the week ending March 2nd, 2012. Without the Vocus-iContact deal, our cloud stocks index would essentially have been flat for the week.

Before we take a closer look at the Vocus-iContact deal let’s go over our standard disclaimer. We maintain the Talkin’ Cloud Stocks Index to analyze cloud hype vs. Wall Street performance. Whether you buy, sell or hold is up to you and you alone.

When Vocus (VOCS) made its iContact acquisition in the middle of last week, I noted that the SaaS marketing tool specialist wasn’t the strongest or most consistent performer on the index. Apparently, that’s translated into weak financials for Vocus, which posted $114 million in GAAP revenue, which was a 19 percent year-over-year boost from 2010.

But that figure still represents “35 cents and 37 cents in per-share earnings for the year, compared with the 85 cents a share that analysts surveyed by Thomson Reuters expected” in 2011, according to the Wall Street Journal. Vocus also is ending its relationship with PR Newswire, even as it looks to boost sales headcount by 60 percent. Combined with the $169 million that Vocus spent on iContact, investors seem to be getting the idea that the company is simply spending too much for too little return.

So here’s the figure you’ve been waiting for: Shares in Vocus dropped to $13.52 by the closing bell on Friday, which represents a big 40.44 percent decline from the week previous. Ouch.

It’s especially a shame since, overall, both the Dow Jones and NASDAQ had banner months in February. And as I mentioned before, if it weren’t for Vocus, our index’s performance would have been relatively flat for the week — not that a 1.51 percent weekly dip is cause for panic, but it’s still worth noting. Take it as an object lesson on the effects a single company can have on an industry.