Congratulations: You’re witnessing history.

I hesitate to employ such a vacuous phrase. You’re always witnessing “history.” Every day’s “history.”

Let me stop before I veer off into some pseudo-philosophical tangent.

The narrow market dynamic that dominates each and every discussion about the never-ending melt-up in US equities has now achieved a milestone of sorts. According to Nomura’s Charlie McElligott, the “negative breadth” streak through December 16 had virtually no precedent, particularly in the context of an index that’s managed a gain over the period in question.

The figures tell the story, but just in case, Charlie told it too, describing “extreme return concentration” as investors chase and herd into the mega-cap tech leadership and “little else.” (It’s worth noting that the Dow, bless its heart, is suddenly mired in a near historic losing streak.)

I realize the left-most chart is the one that catches the eye, but take a close look at the table on the right, above, from McElligott’s colleague Joanna Wang: The current conjuncture’s unprecedented. Shades of 2001 and 2008, only without the market crashes, and instead an ongoing rally.

The scatterplot on the left, below, is another way to visualize the anomalous nature of the current environment. The red marker looks like it doesn’t even belong in the discussion — as if someone just dropped it onto the chart at random.

The chart on the right is straightforward: Just seven names accounted for the index gain over two weeks.

As you can imagine, this is painful for funds who can’t get enough exposure to the leadership. Charlie went on to illustrate the scope of mutual funds’ “under-capture,” for example. Funds’ beta to the Top 50 names and to the Mag7 is near the lows on a two-decade lookback.

Including Broadcom, the Mag8 came into Tuesday comprising 36% of SPY and nearly 52% of QQQ, McElligott added.