Australia's largest online bookseller, Booktopia, has entered voluntary administration and been declared insolvent.

Financial difficulties, including a 22% revenue decrease in the first half of the year, led to this decision.

McGrathNicol has been appointed as voluntary administrators to assess the business and explore sale or recapitalization options.

Efforts to upgrade Booktopia's fulfilment center and the return of co-founder Tony Nash as executive director were insufficient to secure additional funding.

The company's shares, suspended at 45c, have significantly dropped from their IPO value.

Administrators are now exploring options for sale or recapitalization to improve profitability and sustainability.

Shareholder updates will be provided as needed during this uncertain period.