The AIM-listed freight transport firm said the shares would be offered at a placing price of 70p each, an 18.6% discount to its last close price of 86p on July 6, with an aim of raising around £7mln.
The total consideration for the acquisition is £12mln, with £9mln to be paid on completion and £3mln contingent on the future results of ISL and the value of Xpediator shares on 29 May 2020.
The group said the acquisition of ISL would add approximately 40,000 square metres of warehousing, operational synergies and opportunities to cross sell its services, particularly European freight forwarding.
Stephen Blyth, Xpediator chief executive, said: "ISL shares similar characteristics to our previous transactions in that it is a well- established, profitable business which is operating in complementary but sufficiently distinct areas to add to both Xpediator's profitability and service capabilities. ISL's position within the Port of Southampton, in particular, is a significant commercial advantage upon which the enlarged Group can expand.
He added: "It is a natural fit with our business, as there is scope to combine our existing facilities in Southampton, expand our capabilities around port services and provides an opportunity to occupy a further 20k sqm of warehousing space in the future.”