Baltimore—Mobile advertising spending among financial services companies grew 314% on the Millennial Media mobile ad platform in 2011, to become the ad network's most prolific advertising sector. According to Millennial Media's “Mobile Intel Series: Finance” report, financial services companies of all kinds moved ahead of retail and restaurants, entertainment, telecom and automotive in 2011's fourth quarter. Insurance companies led the financial services category, accounting for 42% of the sector's mobile advertising share, followed by banking at 28%. Rather than placing ads next to relevant online content, such as articles about investing or finance, financial services mobile ads tend to appear on general sites, such as weather, maps and search, according to the study, with media-buying choices focused on where target audiences tend to spend their time on mobile devices. Millennial Media's report is based on campaigns on its platform reaching more than 300 million unique mobile users worldwide, according to the company.