Straight Path Communications owns spectrum licenses covering the entire country in the 39 GHz band and additional licenses for the 28 GHz band, both of which are being assigned for next generation 5G wireless networks.

Under a deal with the Federal Communications Commission announced on Thursday, Straight Path (STRP) is paying a penalty of $15 million over the next nine months and surrendering a small portion of its licenses for failing to put the licenses to use as required by federal spectrum rules. The company now has one year to either sell all its remaining licenses and pay the government 20% of the sale price, pay another $85 million penalty, or hand back the licenses to the FCC.

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The company, spun out of telecom provider IDT (IDT) in 2013, said it had hired investment bank Evercore to conduct “a review of strategic alternatives to maximize shareholder value,” Wall Street lingo for exploring a possible sale. That sent shares skyrocketing 34% on Thursday, though the company’s market capitalization is still under $500 million.

“Straight Path Communications’ spectrum is part of the bedrock for 5G and will play an important role in the development of this next-generation ecosystem, underscored by activities already underway by leading wireless carriers and equipment manufacturers in the U.S.,” the company said in a statement announcing the settlement with the FCC.

The FCC had renewed Straight Path’s licenses for another decade of use last year. But anonymous allegations surfaced that the company had misled the agency. An investigation found that wireless equipment had not actually been permanently deployed to put the licenses into use, as required by the FCC and claimed in Straight path’s renewal filings. Straight Path’s total revenue was less than $2.2 million in its most recent fiscal year, which ended July 31, 2016.

FCC officials blasted the company for its behavior. “Squatting on spectrum licenses without any meaningful effort to put them to good use in a timely manner is fundamentally inconsistent with the public good,” Travis LeBlanc, chief of the FCC’s Enforcement Bureau, said in a statement. “Wireless spectrum is a scarce public resource. We expect every person or company that receives a spectrum license to put it to productive use.”

Large telecommunications players—including Verizon, AT&T, T-Mobile (TMUS), and Sprint (S)—are in the process of testing 5G wireless equipment operating the 39 GHz and 28 GHz bands where Straight Path owns rights. AT&T (T) has said it will be testing mobile and fixed wireless applications in both 28 GHz and 39 GHz bands, for example. New 5G networks offer speeds 20 to 50 times faster than current 4G technology.

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The licenses could be quite valuable once cleared of the FCC’s concerns. Verizon (VZ) agreed to pay $1.8 billion last year for XO Communications’ fiber optic network and a leasing deal for XO’s spectrum rights in the same two bands held by Straight Path. Verizon has a $200 million option to buy the spectrum rights from XO through 2018.

The rights were originally auctioned in the 1990s and acquired by Straight Path’s former parent, IDT, from bankrupt wireless pioneer Winstar in 2001.

(This story was updated on Jan. 12 to correct the airwave bands where Straight Path has licenses to GHz.)