NEW YORK: Digital adspend in the US is forecast to reach record levels in 2013, according to new figures from eMarketer, as e-commerce retailers concentrate on holiday shoppers over the last two months of the year.

November and December are expected to account for 23.5%, or $61.8bn, of total US retail e-commerce sales in 2013, up from the $53.7bn recorded for the same period last year.

Buoyed by the holiday season surge, eMarketer estimates total US retail e-commerce sales will grow 16.4% to $262.3bn this year.

With the retail sector spending more on digital advertising than any other industry, it is expected retailers will increase their digital ad budgets by 15.7% to $9.5bn in 2013.

This builds on the 14.5% growth recorded in 2012, although growth rates are forecast to decline over the next four years even if total spend will gradually increase.

US retail digital adspend is forecast to grow by 11.9% next year to $10.63bn, 11% to $11.79bn in 2015, 9.1% to $12.86bn in 2016, falling to 7.5% growth to $13.82bn in 2017.

This year's spending increase is expected to give US retailers a 22.3% share of total US digital ad spending, although retailers' market share is forecast to decline marginally as other sectors catch up.

Mobile advertising, especially on platforms like Facebook and Twitter that offer strong targeting of their large user database, is reported to account for much of the digital ad growth from retailers.

Data sourced from eMarketer; additional content by Warc staff