'I think the bigger impact for us will still be from tables,' Isaacs said. Gavin Isaacs, the chief executive of SHFL, which holds an online poker license for Nevada, said he expects the revenue impact from online poker in the United States to be marginal in the current year, even if it were to start tomorrow. Zynga was one of several companies, including casino games makers SHFL Entertainment Inc and International Game Technology, that have been preparing for the launch of online poker after the Justice Department ruled in 2011 that only online betting on sporting contests was illegal.

Social gaming company Zynga Inc's shares were up 5 percent at $3.53 on the Nasdaq. Shares of 888 Holdings, a partner with Caesars Entertainment, closed up 4.3 percent at 158.5 pence. It was one of the top gainers on Britain's mid-cap FTSE 250 index during trading hours, with volumes double its 90-day daily average. Shares of UK-based bwin.party, the world's largest listed online gaming group, closed up 8.9 percent at 153.91 pence on the London Stock Exchange on Wednesday. Most of the other stocks that benefited from the New Jersey announcement were online gaming companies that have the technology to launch these services in the United States.