Yü, which supplies energy to small and medium-sized businesses, said it had been "significantly oversubscribed" in its placing with institutional investors. Shore Capital is Nomad and sole broker.
The total placing, including the share sale, is valued at £10m, of which the company will receive gross proceeds of £7.5m.
Chief executive Bobby Kalar said: "We have been delighted with the level of support from institutional investors and look forward to welcoming them as shareholders. The placing was significantly over-subscribed which speaks volumes about the quality of business we have built, especially given current market conditions.
"The funds being raised will enable us to accelerate our growth and provide an increasing number of SMEs the energy they need at the right price and with the level of service that they deserve.
"I would like to thank all of our employees whose hard work has enabled us to reach this point and the success of this IPO does them all great credit. Together, we look forward to becoming a publicly listed company and creating value for all of our stakeholders."