International advertising holding company WPP has acquired a controlling interest in fast-growing South African-headquartered marketing agency Quirk, the two companies announced on Tuesday.

The deal, which is still subject to regulatory approvals, comes just months after WPP acquired a majority stake in Cerebra, which specialises in communications and social media.

Quirk was founded 15 years ago as a digital marketing agency by Rob Stokes. Stokes was also the founding chairman of Silicon Cape, an initiative to nurture technology start-ups in the Western Cape.

The value of the Quirk acquisition has not been disclosed.

In a statement, WPP says the decision to buy Quirk is in line with its “strategy of developing its services in fast-growing and important markets and sectors and strengthening its capabilities in digital media”.

WPP’s digital revenues were more than US$6bn in 2013, representing about a third of the total. WPP has set a target of 40%-45% of revenue to be derived from digital in the next five years.

The company has annual billings of $72,3bn and revenues of $17,3bn.

“WPP has been watching Quirk for a while and we feel strongly that now is the right time for us to join forces”, said WPP CEO Martin Sorrell in a statement.

Quirk has five agencies in Africa and London, including a new but growing presence in Kenya. Its clients include Distell, Capitec, Woolworths, Hollard, Makro, Unilever, Caltex and Tyco.