Mr Crabb was the third largest holder in Sigma, the Edinburgh-based group now focused on property and urban regeneration, after West Coast Capital with 22% and chief executive Graham Barnet with 16.5%.
Mr Crabb co-founded Sigma with Mr Barnet as a venture capital group in 1996. It was listed on the Alternative Investment Market in 2000 and spun off Frontier as a university IP commercialisation specialist in 2009.
Of the 3,789,687 shares sold by Mr Crabb, 691,000 were picked up by four Sigma directors, taking the opportunity to buy shares on Thursday after the company announced results.
They paid 6p for each of the shares, which were quoted yesterday as rising 0.25p to 6.62p, which means their combined investment was a modest £41,460.
David Sigsworth, chairman since 2008, bought 165,000 shares, while partnership director Graeme Hogg bought 326,000 and investment director Mark Hogarth bought 100,000. Each of the three now holds a stake of 0.9%.
Marilyn Cole, finance director, holds 1.5% of the company after topping up her holding by 100,000 to 689,660.
At 6p a share, Mr Crabb's holding would have realised £227,381.