"Everyone wants to have them on their [share] register," he said. "While there has been a lot of people talking down Xero, it's really interesting that they've been building up their position. That would seem to be a pretty good endorsement for our long-term prospects."
Drury said other international funds, which he wouldn't name, were also buying up Xero stock.
While Xero is active in four main markets - New Zealand, Australia, the United Kingdom and US - its North American prospects are the main focus for the market.
Xero added 8000 US customers in the six months to March 31 this year, but that growth slowed to only 4000 new US clients in the six months to September 30, prompting downgrades from equity analysts.
In October the company reported annualised revenue of $132.3 million, an 87 per cent increase on the same time a year earlier.
Xero, whose shares recently traded at $16.18, posted a $24.5 million loss for the six months to September 30, compared with a $17.1 million loss in the same period of 2013.
Fidelity has also built up a more than 9 per cent stake in NZX-listed, Christchurch-based healthcare distributor Ebos Group.