Why stockmarkets rise when currencies fall – explained in two charts

The FTSE 100's strong recovery after the Brexit verdict in last June's referendum caught some investors off guard.

After an initial wobble, the index surged. Three months later, it was 10.4% higher. But why?

Other factors may have been at play in those months, but one of the strongest drivers in the fortunes of the FTSE was the performance of the pound.

This is because such a large proportion of profits for FTSE 100 companies is made in dollars. If sterling weakens then dollar revenues, once converted back into sterling, are worth more.

In three months when the FTSE 100 rose 10.4%, the pound fell 12.8% against the dollar.

How the FTSE 100 has risen as sterling has fallen

Source: Schroders. Bloomberg data as at 13/03/2017, showing the FTSE 100 and sterling versus US dollar.. For information purposes only. The material is not intended to provide advice of any kind. Information herein is believed to be reliable but Schroders does not warrant its completeness or accuracy. Past performance is not a guide to future performance and may not be repeated. There can be no guarantee as to the magnitude of any future market movements.

This effect has become more pronounced given the sheer volume of profits earned overseas.

As the chart below shows, 71% of revenues generated by FTSE 100 companies come from outside the UK. The strength of sterling against the euro is also important given the large chunks of revenue accounted for by France, Germany, Italy and other eurozone countries.

The inner ring illustrates that 97% of the companies on the FTSE 100 have registered head offices (i.e. they are domiciled) in the UK.

The outer ring is the important part. It shows the regions from which FTSE 100 companies generate their revenues. All but 28.9% are generated outside the UK.

Advertising firm WPP is among a number of UK-listed companies which have recently announced that their earnings have benefited from sterling weakness.

It can have the opposite effect too. Engine maker Rolls Royce recently announced that its profits were being impacted by weak sterling.

The notion that a falling currency boosts the local stockmarket applies to most markets, but the extent depends on the market's reliance on foreign revenues. The FTSE 100 is a particularly strong example of this, with the dramatic effects of Brexit underlining the point in 2016.