ZURICH - Swiss stock exchange operator SIX Group said on Monday it had agreed to buy Aquis Exchange Plc in a cash offer that put an enterprise value of 194 million pounds ($250.51 million) on the deal, sending the London-based company's shares soaring.

"SIX considers the acquisition of Aquis to be a compelling strategic opportunity which will complement its strategy to scale the exchange business beyond its home markets," SIX said in a statement setting out the terms of the deal.

Under SIX's offer, each Aquis shareholder will be entitled to receive 727 pence per share in cash, more than double Friday's closing price of 330 pence.

Aquis shares leapt more than 114% to 707 pence after opening on Monday.

The Swiss company's offer values the entire issued and future issued share capital of Aquis at about 207 million pounds, and implies an enterprise value of approximately 194 million pounds, according to SIX.

Aquis will continue to operate under its existing brand and business model "with maximum agility", said Bjorn Sibbern, Global Head of Exchanges at SIX.

The offer pays Aquis shareholders a premium of around 68% to the 6-month volume weighted average price of 433 pence per Aquis share as of Nov. 8, SIX said.

Founded in 2012, Aquis operates across areas including a pan-European multilateral trading facility (MTF) for cash equities covering 16 European markets, licensing of proprietary market infrastructure technologies, a UK primary listing growth market and market data, it added.

Aquis' MTF business would extend SIX's presence beyond its home markets, and absorbing Aquis should create "the opportunity for a competitive pan-European listing venue", SIX said.

It should also be attractive to retail brokers and improve execution quality for retail liquidity in Europe, it said.

($1 = 0.7744 pounds)

(Writing by Dave Graham, Editing by Friederike Heine and Louise Heavens)