Investors worry the bull market is getting old. But history shows it can continue to age gracefully.

Bull markets are not living things, and they do not expire on a fixed timetable. The current expansion has run for an unusually long stretch, which has prompted some investors to assume it must be nearing its end. History offers a different lesson: longevity alone has rarely been the cause of a bull market's demise.

What has ended past cycles is typically a change in underlying conditions — a recession, a sharp rise in interest rates, or a sustained hit to corporate earnings. Those are economic events, not the simple passage of time. That distinction matters because it shifts the question from "how old is this rally?" to "what would actually break it?"

For investors, the practical takeaway is to watch the fundamentals that have historically marked turning points: earnings trends, credit conditions, and monetary policy. Age is a talking point. Deterioration in those drivers is the signal worth monitoring.