This Week: How Deep Will Luxury’s Downturn Go?

Shares in LVMH plunged 6 percent last Wednesday after the luxury goods giant reported fashion sales down 5 percent, badly missing expectations. With 75 top-end brands across categories, the conglomerate is broadly seen as a bellwether for the sector, while typically outperforming the competition. Shares in Kering, Hermès and Zegna, all of whom will report third-quarter sales this week, also dropped following LVMH’s miss.

The biggest issue…