The retailer set the strike price for its tender offer at 362p, which represents a premium over Friday's closing price of 357p. All tenders by shareholders at 362p or below will be accepted in full. M&S said it will buy back 27.9 per cent of shares as a result of the tender offer, or£2.3 billion worth.
M&S hopes the deal will help it win the confidence of shareholders, following the rejection of a bid by Philip Green earlier this year.
Numis head of research Ian MacDonald said: '362p is the strike price and this should come as a pleasant surprise to the market. Expectations had honed it on a range of 355p to 360p. In the short term, we aniticipate price weakness. In the long term, our view remains that there is a substantial turnaround potential in this business.'
According to M&S, the deal had been oversubscribed.