Analysts said the latest Kantar data were a “clear measure of the momentum M&S has”.
Clive Black, an analyst at Shore Capital, said: “We’re mid-November now and the fact that trading is so strong gives reasonable visibility that they are well set to trade through Christmas.”
But he added that Mr Machin would not be “resting on his laurels”.
“It’s a very competitive industry and they’ve got quite a long way to go,” he said.
M&S is in the middle of a £480m overhaul of its stores, with plans to upgrade all its 1,500 sites. Mr Black said this would allow M&S to gain an even greater stronghold in the market.
M&S, which is not currently included in publicly available commentary published by Kantar, is expected to be included from next month as it continues to grow market share.
Richard Chamberlain, an analyst at RBC Capital Markets, said the retailer’s “strong innovation” in food was helping M&S to win customers from rivals.
In May, The Telegraph revealed M&S was upgrading 1,000 of its best-selling products this year, on top of the 1,000 it improved last year.
It comes as Waitrose and its parent company, the John Lewis Partnership, battle with turnaround efforts.
Waitrose has unveiled plans to spend £1bn on improving its shops and opening new convenience stores over the next three years. Half of its estate will be refurbished under the plans.
The latest stage of its overhaul is being led by Jason Tarry, the former Tesco chief, who was appointed chairman of the partnership in September.
Nick Bubb, a retail analyst, said: “The John Lewis Partnership has obviously announced these grand plans to refurbish stores, but they’ve got a country mile to go.
“M&S is putting pressure on Waitrose to raise their game and get on with the investment programme.”
Waitrose pointed to separate Kantar data which showed it had outperformed the grocery market in the 12-week period to Nov 3.
A spokesman for Waitrose said: “We’re delighted that the latest Kantar figures show Waitrose outperforming the grocery sector.
“We’ve got momentum behind us with new customers, investment in our shops, a fantastic Christmas range and a festive ad campaign that has been universally well received – so we are full of confidence.”