Shares in US memory chipmaker SanDisk rose nearly 40 per cent on Wednesday after it rejected a $5.8bn takeover bid by Samsung, but showed that it had left the door open for a higher offer.

Eli Harari, SanDisk’s chairman and chief executive, said the $26-a-share all-cash bid was “opportunistically timed at the trough of an industry-wide downturn” and failed to recognise the value of the Silicon Valley company’s patent portfolio.