Investors are being warned of a potential bubble in technology stocks, after a spate of new backdoor listings on the Australian Securities Exchange by start-ups and companies looking for alternative capital raising mechanisms.

Online retailer Deals Direct became the latest technology company to list publicly through an existing vehicle, mobile solutions group Mnemon. It is also the first pure-play online retailer to list on the ASX, despite retailers making up a large portion of Silicon Valley start-ups valued at more than $US1 billion ($1.1 billion).