Groenink caused controversy in the Netherlands for the 24.3 million euros severance pay and sales of shares and options he received on leaving ABN AMRO after hatching the deal which ultimately caused the bank's downfall.
He has stayed largely out of the public eye since then.
According to a statement from Elephant Talk, a US-based business software and services provider for telecoms and financial firms, Groenink is currently a partner of an investment firm, Atlas N.V., and joined Elephant Talk's board of directors with effect from April 1.
The public outcry following his departure from ABN AMRO eventually led the government to introduce restrictions on banker bonuses.
ABN AMRO, now run by former Finance Minister Gerrit Zalm, will be prepared for a listing in 2013, with a possible initial public offering the following year, the finance ministry has said, though it is keeping options open.