Trader Peter Tuchman wears his "Dow 19,000" cap on the floor of the New York Stock Exchange, Monday, Nov. 21, 2016. Richard Drew/AP US stocks opened at all-time highs for a second straight day on Tuesday.

We also got two round-number milestones: 19,000 for the blue-chip Dow Jones Industrial Average, and 2,200 for the benchmark S&P 500. The indexes closed at 18,955.35, (+0.46%), and 2,198 (+0.74%) on Monday.

The last time the Dow, S&P 500, Nasdaq, and small-cap Russell 2000 indexes finished at new highs on the same day was at the height of the dotcom bubble on December 31, 1999.

This rally is a continuation of what analysts are calling the post-Trump rally, which defied forecasts that stocks would fall by as much as 10% if President-elect Donald Trump won. Trump's campaign promises that are considered pro-business — tax cuts, and infrastructure spending for example — are helping to lift market sentiment.

Also, the expectation of higher inflation under the next administration triggered a sell-off in the bond market and a so-called "great rotation" from bond funds to equity funds. This rotation is raising questions about whether the 30-year bull market run in bonds is over.