Riverdeep founder and former schoolteacher Mr Pat McDonagh's shareholding in Riverdeep is now valued at around $270 million (€291 million) following the dilution of his stake in Riverdeep from 43 per cent to 38 per cent.
IBM's stock-for-assets transaction gives Riverdeep a market capitalisation of $701 million compared to $615 million prior to the deal.
The company's chief executive Mr Barry O'Callaghan's shareholding is now worth around $42.9 million, as his stake in the enlarged entity falls from 7 per cent to 6 per cent.
Since it launched on the US Nasdaq and Irish stock exchanges in early March, Riverdeep has been prone to the excesses of Internet stock volatility.
Every $1 change in Riverdeep's share price increases or reduces the value of Mr McDonagh's stake by nearly $14 million.
Since the company floated he has seen the value of his stake soar to $1.03 billion, and collapse back to $230 million within just over a month.
Similarly, the share price has ranged from a high of $72.5 to a low of $16. More recently, the price has hovered around the $20 mark.
Since its flotation, the company has pursued an aggressive strategy of acquisition and alliance. Last month it signed a distribution agreement with UK firm RM (Research Machines) valued at between $15 million and $20 million.
This was followed by the announcement of a strategic partnership to provide content to America Online's schools learning facility, AOL School.
And last week it acquired US language software company, ED-Vantage Software in a $20.1 million cash and stock deal.
In its last quarter Riverdeep reported revenue of $2.2 million, and a loss of $7.3 million.
