Here’s what has driven the Dow rally to 40,000, and why it could keep going

Passing major milestones such as the 40,000 barrier the Dow Jones Industrial Average eclipsed this week makes for a nice headline, but market experts do not take much else from the move.

What really matters is what underpins the market, namely, whether companies are seeing sustainable profits, where monetary and fiscal policy is positioned and what the future landscape is for economic health and specifically the labor market.

Fortunately for the market, most of those variables look pretty positive these days, and are largely behind the blue-chip average’s latest landmark move....