CERE member Christian Ewald, Professor of Mathematical Finance and Economics at Umeå University, is interviewed by Dagens Industri (10 November 2026) about the coming move to near round-the-clock stock trading.
In early December, several US exchanges, Nasdaq among them, will extend their trading hours to 23 hours a day. Some well-known Swedish finance figures have criticised the change, warning that it could bring more volatility and worse price formation. Drawing on his own research, Christian Ewald takes a more positive view. He has studied Brent crude oil futures on the Intercontinental Exchange in London, where trading runs about 22–23 hours a day. His findings suggest that longer opening hours can improve market efficiency.
In the interview, he explains that thin trading at night does not have to reduce liquidity during regular hours. A longer trading day also lets prices react faster to new information. In his view, the bigger risk comes when markets are closed: news pile up overnight and can cause sharp price swings when trading starts again. “From a market efficiency perspective, it is positive,” he says, while adding one condition: all investors need equal access to the market.
He also agrees that private investors may be the most exposed. He points to stop-loss orders as an example, since they do not guarantee a sale at a set price when liquidity is thin. He suggests better information for investors, limits on some order types, and an option to place orders only during regular trading hours.
The full article, “Ekonomiprofessor: Natthandel kan stärka effektiviteten” by Elin Ehrencrona, is on page 13 of the 10 November issue of Dagens Industri and on di.se (paywalled).