(Bloomberg) -- SAP SE’s co-founder Hasso Plattner’s fortune fell by $2.4 billion on Monday after pandemic lockdowns forced the enterprise software-maker to cut its revenue forecast for the year.

The Walldorf, Germany-based company’s shares sank as much as 23%, its biggest intraday drop since 1996. Plattner, 76, is Germany’s seventh-richest person with a net worth of $13.6 billion, according to the Bloomberg Billionaires Index. About two-thirds of his fortune is comprised of SAP shares.

Read more: SAP Shares Collapse After Lockdowns Force Cuts to Revenue

Uncertainty over the economy and the likelihood of a new wave of Covid-related lockdowns prompted SAP to push its targets for total revenue, cloud revenue and operating profit back by a year or two, according to a statement.

Plattner, a programmer, left a job with IBM Corp. to start his first software company in 1972 and turned SAP into Europe’s most valuable technology firm. It makes software that helps corporate clients run their operations, from payroll to expenses to travel requests. He served as the company’s co-chief executive officer until 2003 and is now chairman of the supervisory board.

Plattner’s loss erased all his wealth gains for 2020. Until Monday, his net worth had risen by 6.5%, or $975 million, since January. Overall, the world’s 500 wealthiest people increased their collective fortunes by $960 billion year-to-date through Friday.

©2020 Bloomberg L.P.