Retail sales grew 0.6 percent in May, in nominal terms from a year ago, slowing from 1.3 percent in April, led by a slowdown in service station sales. Excluding those sales, spending rose 1.0 percent in May from a year ago.

Sales at markets, and by mail and internet fell 2.3 percent year-on-year in May after a 1.4 percent decline in April, marking the seventh consecutive decline. Still, there were some positive signs with sales of information and communications goods up 8.5 percent in May from a year ago. Save for one decline in February, sales in the sector have been strong.

The monthly data show sales fell 0.6 percent in May, the fourth consecutive decline this year, with all major sectors reporting lower sales than the previous month.

Clearly the Swiss consumer has been cautious in recent months and will be a drag on second quarter GDP unless there is a surge in spending next month. With continued uncertainty around trade and tariffs, it's unlikely wallets will be opened wide in the coming months.

Retail sales measure the total receipts at stores that sell durable and nondurable goods. The survey comprises around 4,000 companies with the small-sized firms asked to provide monthly turnover data on a quarterly basis. Statistics are provided in both nominal and volume measures; the latter is the more important for financial markets. The headline figure is the annual growth in sales volumes adjusted for differences in trading days. Seasonally adjusted monthly changes are also provided. Details are limited in the first estimate but a more complete picture is provided with the following month's release.

Consumer spending accounts for a large portion of the economy, so if you know what consumers are up to, you will have a pretty good idea on where the economy is headed. Needless to say, that is a big advantage for investors. The pattern in consumer spending is often the foremost influence on stock and bond markets. For stocks, strong economic growth translates to healthy corporate profits and higher stock prices. For bonds, the focus is whether economic growth goes overboard and leads to inflation. Ideally, the economy walks that fine line between strong growth and excessive (inflationary) growth. Retail sales not only give you a sense of the big picture, but also the trends among different types of retailers. Perhaps auto sales are especially strong or apparel sales are showing exceptional weakness. These trends from the retail sales data can help you spot specific investment opportunities, without having to wait for a company's quarterly or annual report.