Forward PE ratio for Equal Weight SP-500 is 17.37, so if the market corrected by say 10% then this would get back into the 15s... which again hardly smells like a bubble...

Morningstar has the forward PE of RSP as 17.26, close to the above value.

Value & Growth Measures   RSP    SPY
    Price/Earnings       17.26  22.49
      Price/Book          2.63   4.55
      Price/Sales         1.65   3.22
    Price/Cash Flow       10.6  15.78
    Dividend Yield %      1.94   1.25
  Long-Term Earnings %    9.37  10.26
 Historical Earnings %    1.04   9.72
    Sales Growth %        6.17   7.98
  Cash-Flow Growth %      0.76   7.14
  Book-Value Growth %     6.01   8.73

Using gtr1, I get a 22.38 PE for SPY on 20251128, which is close to the M* value. (calculated as the sum of market cap divided by the sum of earnings)

Since 1997, the PE for SPY has ranged from 8.63 (on 20081121) to 24.64 (on 19991230), with a 16.45
average value. (Earnings and Market Cap are highly correlated, but the Market Cap seems to drop before the Earnings drop.)

To generate the signals:
1. go to the gtr1 link listed below.
2. click the radio button "Detailed Report".
3. click the check box "Signal Values".
4. click Run Backtest.
5. click Download report.
6. open report (a csv file) with a spreadsheet program.
7. search for "Daily Signal Values" in the report. [EY] column is the earnings yield. PE is 1/[EY].
gtr1.net: GTR1 Backtester - SP500_PEforward

  Date    [sumE]  [sumMC]  [EY]     PE
19971110   0.39     6.85   5.7%   17.66
19981110   0.41     8.47   4.8%   20.77
19991110   0.48    10.71   4.4%   22.55
20001108   0.57    12.48   4.6%   21.74
20011114   0.48    10.12   4.8%   21.02
20021114   0.50     7.87   6.3%   15.80
20031114   0.57     9.73   5.9%   17.09
20041116   0.67    10.80   6.2%   16.03
20051115   0.80    11.38   7.0%   14.29
20061115   0.87    12.81   6.8%   14.66
20071116   0.95    13.18   7.2%   13.82
20081117   0.79     7.92   10.0%  10.01
20091117   0.70    10.08   7.0%   14.36
20101117   0.88    10.84   8.1%   12.32
20111116   1.02    11.78   8.6%   11.57
20121119   1.06    12.61   8.4%   11.92
20131119   1.13    16.53   6.8%   14.67
20141119   1.19    18.82   6.3%   15.77
20151119   1.17    19.12   6.1%   16.38
20161118   1.17    19.38   6.0%   16.53
20171120   1.29    22.95   5.6%   17.82
20181120   1.54    23.55   6.6%   15.26
20191121   1.53    26.75   5.7%   17.50
20201120   1.42    30.85   4.6%   21.66
20211122   1.94    41.67   4.6%   21.52
20221122   2.02    34.53   5.9%   17.09
20231124   2.13    39.57   5.4%   18.57
20241125   2.41    52.31   4.6%   21.68
20251128   2.73    61.00   4.5%   22.38