Spark NZ yesterday briefly reclaimed the top spot as the most valuable company on the NZX, a position it once firmly held in its previous incarnation as Telecom.
Shares in Spark have surged 33.6 per cent this year to $3.12.
Spark NZ chief executive Simon Moutter said the rising share price indicated the company's rebrand and new focus was working.
"I think [the share price growth] is mostly to do with our clear articulation of strategy and solid execution against that," Moutter said.
"The commentary from the public has been very positive around the way we handled the rebranding of the organisation, and certainly our internal measurement of progress is indicating that the customer response is very positive," he said.
"I think there's a growing sense that we've got the company on a positive track."
The company has the fourth-highest growth in share price this year, behind OceanaGold Corp, Meridian Energy and F&P Healthcare.
At one point during trading yesterday afternoon, the company's market capitalisation passed leader Fletcher Building, putting the company briefly in the top position.
"It's some years since we've been number one on the NZX," Moutter said.
"This time last year we were number four behind Fletcher Building, Auckland Airport and Xero, but we briefly [yesterday] had the highest market capital on the NZX, so that's the outcome of a positive track on investor sentiment, which was a fun moment.
"We're in the process of reclaiming the number one position on the NZX," he said.
Moutter said there had been no recent updates or forecasts which would explain the rise of the share price, and attributed the growth to a rising confidence from investors in the company as well as a successful execution of their new focus.
"For an organisation that's been searching for a way forward for a decade, and a way back to being the brand that New Zealanders are proud of and want to be with, these are the signs of success."