After the January 1966 coup, he joined the Nigerian Industrial Development Bank. At NIDB, his interest in investment banking led him to advocate for the establishment of merchant bank sponsored by NIDB. When ICON securities, a merchant banking outfit was established in 1973 as a subsidiary of NIDB, Balogun moved to ICON Ltd as a director of operations. When Balogun's ambition to head ICON was not realised, he left he firm to found City Securities, a stock broking and issuing house. City Securities developed relationships with Mobil, Texaco and Total petroleum marketing companies, handling the companies equity offerings. In 1979, he applied for a merchant banking license to establish First City Merchant Bank. Balogun was inspired by the entrepreneurial works of Siegmund Warburg, who co-founded S.G. Warburg, he visited Warburg in London prior to establishing his merchant bank. He often tells the anecdotal story of how his son inspired him to take the leap in starting the bank. When the operations of the bank took effect in 1983, Balogun established an entrepreneurial culture at the new bank, unique as an owner managed bank in contrast to the government owned banks at the time.