Brick-and-mortar retailers have been facing constant threats from digitalization. The surge in web-based shopping is severely affecting sales at departmental stores, resulting in store closures and filings of bankruptcy. Over the past decade, worldwide e-commerce has been growing at an average rate of 20% a year, according to Economist.

As of now, online retail sales make up about one tenth of total retail and about 5% of annual e-commerce revenues in the United States. The space is developing fast, courtesy of increased usage of smartphones and other mobile Internet devices.

Per Statista, in 2016, 58.3% of global Internet users had bought products online; the number is expected to increase to 63% by 2019. More than the United States, the real growth opportunities lay in the under-penetrated emerging markets. With digital buyer penetration likely to exceed 65% of Internet users globally in 2021, the e-commerce industry is set to expand.

Per Statista, e-commerce share of global retail sales will likely go up to 17.5% in 2021 from 10.2% in 2017. Last year, global retail ecommerce sales were $2.304 trillion, marking a 24.8% year-over-year increase, per eMarketer. Mobile was the main driving factor and by 2021, m-commerce is likely to account for about 72.9% of the ecommerce market.

In particular, eMarketer estimates that U.S. ecommerce sales will grow 15.6% in 2018 to reach $526.09 billion, 14.8% in 2019, 14.3% in 2020, 13.9% in 2021 and 13.3% in 2022. While 10% of total retail sales are likely to be done online in 2018, the number is expected to rise to 11.1% in 2019, 12.4% in 2020, 13.7% in 2021 and 13.3% in 2022.

Another firm, Forrester, expects U.S. online sales to cross $506 billion this year and rise beyond $712 billion by 2022. More than half — 53% — of the $3.7 trillion U.S. retail market will be accessed digitally by the end of 2018. More than $1.3 trillion of U.S. retail sales will likely be driven by smartphones in 2018, per the source (see: all the Consumer Discretionary ETFs here).