The Dow broke another record yesterday and is now on its longest record-breaking streak — six days — since 1998. And while that all sounds great, one man is not happy.

Allan Sloan, senior editor-at-large at Fortune magazine, is focusing instead on the four-year anniversary of the market bottom.

“The mood was suicidal, the market was crashing, people were scared,” Sloan says. “[But] I learned that nothing is forever.”

According to Sloan, today’s booming market could use a healthy dose of that suspicion.

“I am a student of history, I’ve seen people stampede up, I’ve seen people stampede down,” Sloan says. “What I try to do is to be half a cycle out of phase.”

To hear more investing tips from Allan Sloan, click on the audio player above.