PARIS — Hunker down.

At a time when Christmas lights have started appearing in London, retailers in France and Italy boarded up their stores and curtailed opening hours on Saturday in preparation for another day of major protests , following the previous weekend’s demonstrations during which thousands of stores were damaged or looted.

Although Saturday’s marches in both countries were mostly peaceful, with isolated pockets of violence, the retail sector was left tallying the cost of lost business in the runup to the crucial holiday season — not to mention additional expenses linked to increased security measures. The lost business came on top of the costs of repairing the damages from the Oct. 17 marches.

“Compared with last Saturday, yesterday was a relief.…