“ Sell in May and go away ” might be a favourite saying of the City, but those who might have followed the advice this year would have left a lot of money on the table as the FTSE 100 has surged ahead . Currently, London’s main market is up 1.7 per cent since the start of May, while the more domestically-focused FTSE 250 has fared even better, rising 3.

7 per cent. While this isn’t as good as the FTSE 100’s excellent last two months, where it jumped 3.3 per cent and 2.

4 per cent, it still represents strong growth for the market. “Sell in May and go away, don’t come back until St Leger’s Day” is an often quoted adage, but analysis has found it doesn’t actually hold up in practice. So, which companies have led the market higher? BT Group has charged ahead of the FTSE 100, rising over 25 per cent in May after shares surged on the back of bullish guidance halfway through the month.

The telecoms company reported a strong fibre roll out – it added a record 78,000 new customers a week to its network. Chief executive Allison Kirkby said: “I always love to squeeze the shorts..

. and prove them wrong”. Marks & Spencer was the runner up of the month.

The stock added 18.8 per cent, after it revealed a jump in annual profit last week thanks to buoyant sales across its food halls and clothing and home arm. Meanwhile, Auto Trader, which added 18 per cent, and St James’s Place, which added 16 per cent, were the third and fourth top performers in the FTSE 100 respect.