Google's Android mobile operating system has grown its market share lead, according to new data from Gartner. Indeed, the research firm says the platform accounts for 74.4% of smartphone units sold worldwide during the first quarter of 2013. Furthermore, Gartner found there are almost 50% more Android smartphones in the market than a year ago.

Banks are aware of this clear dominance and continue to develop mobile banking apps for Android devices, but are wary of security issues, Gartner analysts say.

"The popularity of Android from a B2C perspective makes it a priority next to iOS when it comes to developing applications," wrote Carolina Milanesi, research vice president of consumer technology and markets at Gartner, in an email to BTN. "From an IT perspective, we still see some concerns in financial services about deploying Android due to fragmentation on the OS side and security vulnerability of Google Play, which remains a non-curated environment."

Bankers BTN spoke with today place equal importance on developing features for iOS as they do for Android, including the fourth largest bank by assets: Wells Fargo & Co. (WFC).

"We think about customers first and where they are," says Armin Ajami, vice president and senior product manager with Wells. "In the U.S., Android is in a leadership position."

Wells has had an Android app since 2010. That app, along with its iPhone app, are the most popular platforms with customers, reflecting overall industry trends. Enhancements to the platforms are made around the same time. "We look at the two leading platforms together," Ajami says.

Wells counts more than 10 million mobile customers, but does not break out those numbers by platform. Regarding user patterns, Ajami points out iPhone customers are more engaged than Android customers.

Like Wells, other banks view Android as a leading platform that they must — and have been — developing natively for.

The Android platform's "substantial market position is pretty well established now," writes John Schulte, senior vice president and CIO Mercantile Bank in Michigan, in an email to BTN. "We have felt for a while that we need to maintain a native app presence on all Android phones/tablets, including the Kindle family."

The bank is currently focused on responsive design for all of its web content so that it renders well regardless of the various device screen sizes that have popped up in the last few years, said Schulte.

Bank of Montreal (BMO), meanwhile, says it designs for Android, iOS and BlackBerry within a similar timeframe. "We don't want to leave devices behind," says Dan Dickinson, head of online and mobile banking for Canada at BMO.

Looking ahead, Dickinson says the bank is looking at how it might make use of Android's widgets to display information outside of the login. "You have to tread carefully there," he says. Early ideas include displaying personal finance management (PFM) tools or rewards information within the widgets.

Gartner estimates that Android was on three-quarters of all smartphones sold in the first quarter of 2013, led by sales from Samsung. The closest competitor was Apple's iOS at 18.2% while Research in Motion took third by grabbing 3% of the market share, according to Gartner's data.

In the U.S., the Android market share is estimated lower than Gartner's worldwide numbers, though the platform still rings in as the leader. ComScore numbers released in May show that Android, with 52% market share, ranked as the top smartphone platform, while Apple's share came in at 39%, followed by Blackberry with 5.2% market share.

Meanwhile, Javelin Strategy & Research's January report showed Android smartphones and tablets claim 48% of the U.S. mobile market, up from 34% last year. Apple's iOS market share was 32%. Despite the platform's lead, the firm found that banks are more reticent to develop for Android than they are for iOS.