Australian start-ups raised $1.5 billion across 99 deals in the three months to June 30, making it the sector’s strongest quarter in 18 months, thanks to the return of mega venture capital deals. But in a two-speed sector, some are struggling to meet investors’ high expectations.

After a slow start to the year, six local start-ups closed deals worth more than $100 million to raise a combined $935 million in the second quarter, new data from Cut Through Venture shows.