Independents took the biggest hit, alongside department stores, which also struggled to keep up with the rest of the high street.
However, total clothing and footwear sales were up for the period, with growth of 4% reported this autumn.
TNS consumer insight director Anika Davies said: “The independent sector has been having a tough time because it has had to compete on price during a year when the value sector has performed strongly. However, the good performance in the value market has fallen back recently.”
According to TNS, the average price of goods in independents was £20.38, compared with £9.26 in the total market over the period.
Kidswear sales were flat against last year, but menswear was the best performer, with sales up 5%. Discounted womenswear sales grew 14% over the period.
Multiples experienced the strongest growth in the retail sector, with market share up 0.6% over the 12-week period. General stores, which include Marks & Spencer and Bhs, also gained market share. Discounters’ market share dipped for the first time since July 2005, which has been attributed to customers trading up.
However, the supermarkets share of the clothing and footwear market increased to 7.4% over the period. The report predicted that the discount and value sector would come up against stronger comparatives next summer.