Do I hear 20,000? 21,000? That's the subject Wall Street investors are starting to consider after post-election ebullience has stretched equity markets deeper into the record books since Nov. 8. Assuming that the indexes continue to lurch forward into the next week or two, that puts the gauge on pace to log the fastest 1,000-point rally since the Dow moved from 10,000 to 11,000 in from March 29, 1999, to May 3, 1999 — a 24-day trading day span, according to Dow Jones data. The broad-based rally has been supported by the expectation that Trump will unleash a raft of...