McAfee on Tuesday announced it is acquiring NitroSecurity, a privately owned security information and event management provider based in Portsmouth, N.H. McAfee said that following the buy, which is subject to regulatory approvals and other customary closing conditions, the integration of NitroSecurity’s technology into McAfee ePolicy Orchestrator will give organizations greater visibility into their IT environment. The acquisition is expected to close by the fourth quarter of this year. During 2010, the SIEM market grew from $858 million to $987 million, a growth rate of 15 percent, according to Gartner.