Next week, Y Combinator will hold its 35th Demo Day. Tech start-up founders will have just one minute to present their ideas to potential investors. This year the stakes are particularly high, as new chief executive Garry Tan will be aware. His recent appointment coincides with a sharp downturn in start-up investment.

In the second quarter of the year, global start-up funding fell 23 per cent from the previous quarter to just over $108.bn, according to CB Insights. Megaround investments of $100mn or more fell almost a third. This drop reflects the fall in public market share prices. In May, Y Combinator warned start-ups to plan for the worst.

So-called accelerators live at the sharpest end of the start-up funding ecosystem, backing ideas that may not yet be products. Few make it to the next round of funding. The rise of software companies that do not carry big upfront costs has made the business of early-stage investing more lucrative. But if venture capital firms reconsider their investment plans, accelerators could struggle to sell their start-up stakes.