You're not imagining things—there is more spam in your inbox these days.
A report released Monday by the computer security firm McAfee found that global spam volume is on the rise—and in the United States, it's being driven by surprising financial market catalyst.
According to the McAfee Threats Report for the first quarter of 2013, spam email volume rose "dramatically" in that time frame after three years of stagnation. One significant element driving the growth in North America, the firm said, was "the return of 'pump and dump' spam campaigns."
Those campaigns are designed to quickly focus investor attention on an obscure, thinly traded stock to create a sharp run-up in value. Typically, those scammers will buy the stock before sending the spam and then sell after the price pops, pocketing a quick profit.
And part of what's driving this surge in spam is scammers targeting people who are frustrated that they've missed out on the gains from the recent surging bull market. McAfee said it has spotted an increasing number of spam emails targeting would-be investors "hoping to capitalize on all time equity market highs." Also contributing to the surge: growth hormone offerings and increasing spam campaigns in emerging markets.
"Spam promoting pump-and-dump stock schemes was way up this quarter, no doubt riding the recent market wave to appeal to unwary investors seeking higher gains," the report noted. "But it's never a good move for traders to get involved with these types of stocks."
Overall, McAfee said it counted 1.9 trillion spam email messages in the month of March—lower than record levels but about twice the volume the firm saw in December.
Another area of growth, said McAfee, was malware programs designed for mobile devices. The firm captures samples of malware programs that it spots and keeps them in a cyber "zoo" for analysis. It said it now has 50,926 examples of mobile malware in its zoo, and 28 percent of those programs arrived in 2013. That compares with only 792 in 2011.
_ By CNBC's Eamon Javers. Follow him on Twitter: