Shares in Britain's B&M European Value Retail, chaired by former Tesco chief executive Terry Leahy, rose 6% on their market debut.
The rise showed that investors remain enthusiastic about the discount sector of the UK retail industry.
B&M, which sells products ranging from bedding to barbecues from more than 370 stores, was trading at 285 pence this morning after selling its shares at 270 pence.
That valued the fast-expanding group at more than £2.8 billion, nearly £2 billion above its main discount rival Poundland, and £1.2 billion higher than Argos owner Home Retail.
B&M reported adjusted core earnings of £130m in the year to the end of March, up 24%, on sales of £1.27 billion.
Chief executive Simon Arora has said two-thirds of the British population did not have easy access to a B&M store and there was room for around 850 stores across the UK.
"We are delighted that investors have demonstrated their support for B&M and its growth story in the value sector and that they share our excitement about the group's future," he said today.
Poundland, which sells all items for £1 rather than B&M's varied prices, saw its shares jump on its market debut in March. While they have lost some of the initial surge, the yremain 44% above the float price of 300 pence.
Proceeds from London IPOs have more than trebled this yea rto $8.8 billion across 33 listings, according to Thomson Reuters data.
Other retail offers have fared less well since listing. Pet sat Home, which floated at 245 pence in March, trade sat 219 pence today, while online appliance retailer AO World is also losing ground, with its shares valued at 259.75 pence against a 285 pence listing.
Former Tesco boss Leahy left Britain's biggest supermarket chain in 2011, joining B&M in 2012. Tesco has since suffered a costly exit from the US and sliding sales while discounters have gained market share.