Mr Rybinski, who had joined the business from Parmalat, was recruited by the recently departed chief executive Jayne Hrdlicka and only took up the CTO role at the business in May.
A2 Milk said Mr Rybinski was leaving the company to pursue other interests and until a replacement was found, chief operations officer Shareef Khan would assume responsibilities for all technical functions, the company said in a statement to the stock exchange.
The departure comes on the same day as former Qantas Airlines chief financial officer Race Strauss begins his new job as the company’s chief financial officer, with previous CFO Craig Louttit becoming his deputy.
The new-look leadership team includes former a2 boss Geoffrey Babidge, who returned to the top job in December when Ms Hrdlicka, a former CEO of Jetstar and Bain & Co managing consulting partner who had been in the CEO role less than 18 months, agreed to step down.
The company has also been scouting for a new marketing head, after its inaugural chief marketing officer Susan Massasso announced in November she would be leaving the company in mid 2020.
Critics of Ms Hrdlicka believed she was too willing to spend on consultants as part of her vision of trying to build an ”in-country” presence in China for a2 formula, rather than relying on the capricious daigou trade, which had bought up tins of formula in locally to sell online in China.
Spending on consultants had reached $NZ20 million ($19.4 million) by last June 30, while marketing costs hits $NZ135 million.
In an interview at the time of his re-appointment to the top job, Mr Babidge said he would evaluate the spending on consultants, wanting to satisfy himself that the output of the consultants justified the cost.
The company has been one of the best growth stocks on the ASX in the last five years, going from only 56¢ to more than $14.
But in June fears were sparked amongst investors in infant formula companies, when China’s National Development and Reform Commission released a plan to bolster the amount of Chinese-produce formula from 47 per cent of the market to 60 per cent.
At the time it resulted in a significant share price fall for the company, going from a high of more than $17 in June to $11.30 in November, but since then it has bounced back to be trading around $14.30.