Aquis Exchange PLC (AIM:AQX) has agreed to be bought by Switzerland's SIX Exchange for 727p per share in cash, valuing the whole business at £225 million on a fully diluted basis.
The two boards said a recommended cash offer has been arranged at a price that is more than double the 330p closing price last Friday and 68% above the six-month average price of 433p, and above the 500p one-year high seen in July.
Aquis founder and CEO Alasdair Haynes said he is "immensely proud of the business we have built" after launching it as a startup subscription-based exchange in 2012.
"Aquis has a clear path of growth ahead; however, the Aquis directors recognise there are always some operational, commercial and market risks associated with the timing of future value creation.
"The offer de-risks this future value creation and provides Aquis Shareholders with certain value at a material premium."
As part of SIX, he said Aquis would have be able to accelerate the development of the business and "compete more effectively on the European stage, while retaining our entrepreneurial spirit".
SIX said Aquis will continue to operate under its existing brand and business model.