Greg Smith, head of research at Fat Prophets, said the reaction wasn't surprising and was effectively another strike in the market's eyes after a weak first-half result.
"It is a 13 per cent miss at the bottom end versus previous guidance, and at 30 times FY20 earnings the stock will always be vulnerable to disappointments," Smith said.
"There may also be a concern that project/contract 'Delays' may prove euphemistic and more permanent in nature, or that risks in the UK are on the rise, with the economy there a hot topic given Brexit."
In May, Gentrack reported a 19 per cent decline in first-half ebitda to $12.8m, even as revenue increased 5 per cent to $54.4m. At the time, the company said revenue growth was slowing as it generated more software-as-a-service sales, and as some customer projects were deferred.
The company reported a first-half loss of $8.7m after writing off the carrying value of airport software developer CA Plus, which it bought in 2017.
As at March 31, Gentrack reported $32.1 million of receivables, of which $18.3m was from trade debtors and $11.9m from contract assets. At the time, it provided for $679,000 of impairments and $137,000 for warranty claims.
Gentrack didn't provide a bottom-line profit forecast.