Like the firms they work with through Square 1, investors are looking for an “exit.”

Durham-based Square 1 Bank, which launched in 2005 and has grown steadily over the years to develop a national presence while focused on clients related to the venture capital industry, plans to go public with a stock offering. 

On Tuesday, Square 1 disclosed that it had filed paperwork with the Securities and Exchange Commission to take the privately held financial institution public.

Square 1 Financial, the holding company for Square 1 Bank, filed the notice.

If successful, Square 1 shares will trade on the Nasdaq under the symbol “SQBK.”

However, Square 1 disclosed few other details such as number of shares to be offered and a price range for the stock,

A prospectus has yet to be filed.

The IPO would be the latest in a series of successful offerings by Research Triangle-area firms, including Quintiles and ChannelAdvisor, which went public in 2012. Two regional biotechs also recently filed to go public.

Square 1 said Sandler O’Neil & partners will handle the IPO with assistance from Keefe Bruyette & Woods.

The filing of the IPO represents the latest sign of growth by Square 1, which raised more than $23 million from investors in 2012 and $48.5 million in 2010.

Just last week, the firm expanded its services capabilities by acquiring an accounts receivable financing solutions firm in Silicon Valley.

Financial terms of the deal for Sand Hill Finance were not disclosed.

Square 1 says it has hired “all employees” of the firm and acquired “substantially all of the assets.”

The bank is run by Doug Bowers, who replaced founder Richard Casey. Casey died in 2010. Bowers, a 25-year veteran at Bank of America, took over as CEO in March 2011.

A team of Square 1 executives had run the bank since Casey’s death the previous November.

“We are very pleased with the success of this capital raise and the expression of continued confidence from our larger investors,” Bowers said in a statement when Square 1 raised its new capital in 2012. “The additional capital will allow us to continue our organic growth, focus on strategic initiatives, and propel the Bank forward.”

Bowers said the willingness of investors to buy the additional shares reflected the bank’s performance.

“Over the past seven years, Square 1 has experienced significant growth within our loan portfolio, while maintaining excellent credit quality and a strong balance sheet,” he added. “We are excited about the opportunities we see in our markets, and remain committed to delivering unparalleled banking services to companies in all stages of growth.”

Casey had raised $105 million in capital from some 200 shareholders to get started.

The bank opened with six offices and 45 employees.

It  now has offices in Austin, Boston, Denver, Los Angeles, New York, San Diego, Seattle, Silicon Valley and Washington, DC.

Casey was a former executive with Imperial Bank in California where he worked in the venture division. That group was founded to compete in part with Silicon Valley Bank, another firm focused on technology startups. Imperial was bought by Comerica in 2001.