Towerstream, which has a market cap of about $185 million following the offering, provides wireless broadband to businesses in a dozen cities, including Boston, Chicago, Los Angeles, Miami and New York. It is also developing "small cell" networks, which range from Wi-Fi nodes to distributed antenna systems in spots where traditional wireless towers coverage is problematic.

The company closed the stock offering on Tuesday, Feb. 5, and has said in Securities and Exchange Commission filings that it may use cash or equity to make purchases.

The funds could also provide insurance against cash burn as Towerstream develops its business. While the company operates in a high-growth business and has a surplus of cash, there have been concerns that it could run out of funds while investing in networks.

Towerstream has about $30 million in revenue. Since 2010, it has purchased small Los Angeles wireless broadband business Color Broadband and networks from three other companies.

D.A. Davidson & Co. analyst Donna Jaegers said in a February note that Towerstream will likely target roof-top leases to expand its Wi-Fi network, alongside other small-cell assets. D.A. Davidson was a co-manager of the offering.

Towerstream created a new business, called Hetnets Tower Corp., to hold these niche assets in January.

When founded in 2000, the company focused on fixed-wireless service that provided broadband coverage to offices.

It later expanded into Wi-Fi and distributed antenna systems, or DAS.

DAS networks are bundles of wireless antennas that are connected by fiber. They are often deployed in stadiums, hospitals or malls, or other areas with dense mobile usage.

Small-cell networks have attracted private equity and corporate buyouts.

Lisle, Ill.-based ExteNet Systems Inc. has backing from Soros Funds Management LLC, tower operator SBA Communications Corp. and VC firms Centennial Ventures, Columbia Capital, Sevin Rosen Funds, CenterPoint Ventures and Palomar Ventures.

Another company with DAS systems, InSite Wireless Group LLC, is backed by Catalyst Investors and Cox Communications Inc.

Wireless tower operator Crown Castle International Corp. has aggressively pursued DAS assets. It bought NextG Networks Inc. from Madison Dearborn Partners LLC for $1 billion in 2012, and paid $128 million for NewPath Networks Inc. in 2010.

Jaegers noted that Towerstream "had been adamant about not wanting to sell more stock at this level" and questioned why the company sold the equity.

The stock traded at $2.86 per share on Thursday. In January it had traded as high as $3.85 per share.

Extrapolating from Crown Castle's purchase of NextG, she wrote that the small-cell business that Towerstream has been building could be worth $228 million.

The analyst would value the wireless broadband business at 5 to 6 times its $5.7 million in estimated 2013 Ebitda, or between $28 million and $34 million.

Revenues have lagged despite recent contracts with carriers, Jaegers noted, while investments in Wi-Fi are using up cash.

At the close of the third quarter, Towerstream had $23 million in cash and $2.4 million in long-term debt. The bear argument suggested that Towerstream could run out of cash.

Lazard Capital Markets LLC ran books for the offering, and Canaccord Genuity Inc. and D.A. Davidson were co-managers.