As Zynga co-founder and chairman Mark Pincus returned to the role of CEO with the company, usurping 2013 recruit Don Mattrick in the process, the social gaming pioneer’s stock market woes continued.

Zynga’s shares, listed on the US S&P 500 index, fell 18 per cent on Thursday – the day after Pincus’ return was announced – to $2.38 a share.

The shares had already lost around 30 per cent of their value in the 12 months prior to yesterday’s fall.

Image: Mark Pincus, Zynga's returning CEO