Nearly one year ago, privately held experimental small modular nuclear reactor (SMR) company X-Energy announced plans to reverse-merge itself into special purpose acquisition company (SPAC) Ares Acquisition Corporation (NYSE: AAC) in a $2 billion transaction targeting a nuclear power market that could be worth $1 trillion by 2050. On Tuesday, X-Energy and Ares Acquisition announced they have mutually agreed to terminate their business combination -- and as of 10:15 a.m. ET, Ares stock is up 9.2% on the news. Despite X-Energy saying it has "received strong interest from potential investors," the two companies were convinced by "challenging market conditions [and] peer-company trading performance" that now is not a propitious time to bring a nuclear power company public.