Dixons Carphone, the electrical goods and mobile retailer, has said trading over Christmas was a "rollercoaster" but it has predicted a higher-than-expected profit for the full year.
The firm - owner of Currys, PC World and Carphone Warehouse - now expects pre-tax profits of £355m to £375m, above its previous forecast of £354m.
It said group like-for-like sales, which strip out new store openings, rose 7% in the nine weeks to 3 January.
It also gained market share.
"The strange shape of this year's Christmas trading was something of a rollercoaster but I am very pleased with the end result," said Dixons Carphone chief executive Sebastian James.
He said the "huge scale and success" of its Black Friday promotion affected trading for the following three weeks, but customers then responded positively to its Boxing Day deals.
The firm said it had also seen some shifts in the way people shopped, with online sales growing.
It also said laptop sales grew over the Christmas period, while tablet sales "fell sharply", which the retailer put down to "less innovation" in the category.
The company was formed last year by the merger between Dixons Retail and Carphone Warehouse.
Richard Hunter, head of equities at Hargreaves Lansdown Stockbrokers, said the strong performance showed the tie-up between the firms was justified.
"The complementary businesses each contributed to a strong group performance. Competition in the sector will remain intense, but with Dixons Carphone trading strongly and bearing down on cost synergies, prospects for the company remain bright," he said.
Dixons Carphone was just one of many retailers reporting Christmas trading updates on Wednesday:
- WH Smith reported a 2% fall in like-for-like sales for the 20 weeks to 17 January, but said its profit growth was on track, and its travel section, which includes airport and rail station stores, saw sales rise.
- Poundland said it had "another good quarter of sales growth and a record Christmas trading period" with total revenue, excluding Spain, up 9.8% in the 13 weeks to 28 December. It said it was on track to open 60 net new stores in the financial year.
- Pets at Home said like-for-like sales rose 4.1% in the 12 weeks to 1 January, and said it opened seven new stores, meaning it now has 392 stores in total.
- Halfords reported a 6.7% rise in like-for-like sales in the 15 weeks to 9 January, with car maintenance products and children's bikes the standout performers.