NEW YORK: Retailers in the US must respond to major trends like the rise of multichannel sales, "polarised" spending and the increasing affluence of Hispanic shoppers, according to McKinsey.

Despite the "hype" about ecommerce, McKinsey said multichannel sales - offline purchases influenced by online research - constitute the fastest-growing retail category, now impacting $1tr worth of bricks and mortar revenues, double the 2007 total.

Overall, multichannel and ecommerce returns currently make up 45% of all retail expenditure, and are expanding at around 19% per year, according to the consultancy's figures.

Another identifiable shift is "polarisation", as consumers at the high- and low-ends boost their outlays, while middle class shoppers cut back. The fact that savings rate has hit 5% also shows a change in emphasis among buyers.

"Customers are increasingly 'straddling' their spending habits, going to value on the basics and paying a premium for those categories and brands that demonstrate differentiation," McKinsey said.

Demographics also have a role to play, as the number of people aged over 65 years old is due to climb from 40m to 55m between 2010 and 2020. In this period, the amount of 55-64 year olds will similarly climb by 8m.

The under-35 year old cohort should add an additional 11m people. Millennials, born between 1985 and 2004, will remain the largest single group on 79m, as well as the most brand loyalty and liberal in terms of expenditure.

Equally, the growing number of Hispanic households - and their rising affluence - means this segment will take 30% of US income by 2020, up from 9% in 2009, presenting an attractive audience for brands.

Elsewhere, obesity is becoming a pressing problem. In 1990, no US state had an obesity rate of more than 15% but by 2008 only Colorado was still in this position.

Alongside driving sales of health and pharma goods, sectors such as sporting equipment and fitness apparel may see an increase in demand, be it from "overweight people trying to slim down or slim people trying to stay that way".

Green products are likely to witness an equivalent hardening of interest, the study suggested, as shopper habits reach a "tipping point" in this area.

An additional trend outlined by the study was the need to exploit "big data" across digital media. McKinsey reported that retailers effectively using this material could see their net margins increase by nearly 60%.

Data sourced from McKinsey; additional content by Warc staff