Observatory · observe first
Iron Mountain
IRM · United States · Other Specialized REITs · matched S&P 500 member. Follow its market-weight contribution.
Historical time machine
Historical observation
20182026
Universe weight
0.044%
12M weight contribution
-0.016 pp
3M weight contribution
-0.004 pp
12M price return
+22.9%
Share of matched S&P 500 members
Monthly observations through Mar 2026
Company price index
A separate dimension from market allocation
Historical observations
Most recent 24 observations at or before the selected month
| Month | Market cap | Universe weight | 12M weight change | 12M return | Above 6M weight average |
|---|---|---|---|---|---|
| Mar 2026 | $30.2bn | 0.044% | -0.016 pp | +22.9% | No |
| Feb 2026 | $32.0bn | 0.044% | -0.017 pp | +20.5% | No |
| Jan 2026 | $27.2bn | 0.052% | -0.014 pp | -6.0% | No |
| Dec 2025 | $24.5bn | 0.048% | -0.022 pp | -18.2% | No |
| Nov 2025 | $25.5bn | 0.050% | -0.030 pp | -27.9% | No |
| Oct 2025 | $30.4bn | 0.060% | -0.026 pp | -14.1% | No |
| Sep 2025 | $30.1bn | 0.060% | -0.021 pp | -11.5% | No |
| Aug 2025 | $27.3bn | 0.057% | -0.024 pp | -16.0% | No |
| Jul 2025 | $28.7bn | 0.061% | +0.007 pp | -2.2% | No |
| Jun 2025 | $30.3bn | 0.065% | +0.016 pp | +17.9% | Yes |
| May 2025 | $29.1bn | 0.066% | +0.021 pp | +25.9% | Yes |
| Apr 2025 | $26.3bn | 0.063% | -0.002 pp | +19.1% | No |
| Mar 2025 | $25.3bn | 0.060% | -0.005 pp | +10.4% | No |
| Feb 2025 | $27.4bn | 0.061% | -0.005 pp | +21.9% | No |
| Jan 2025 | $29.8bn | 0.066% | +0.008 pp | +54.7% | No |
| Dec 2024 | $30.8bn | 0.070% | +0.009 pp | +54.5% | No |
| Nov 2024 | $36.3bn | 0.080% | +0.022 pp | +98.9% | Yes |
| Oct 2024 | $36.3bn | 0.085% | +0.027 pp | +116.1% | Yes |
| Sep 2024 | $34.9bn | 0.081% | +0.023 pp | +106.2% | Yes |
| Aug 2024 | $33.2bn | 0.080% | +0.021 pp | +84.7% | Yes |
| Jul 2024 | $30.1bn | 0.054% | +0.015 pp | +73.1% | No |
| Jun 2024 | $26.3bn | 0.049% | +0.011 pp | +63.4% | No |
| May 2024 | $23.7bn | 0.045% | +0.007 pp | +57.1% | No |
| Apr 2024 | $22.7bn | 0.066% | +0.011 pp | +45.9% | Yes |
Its weight is estimated market cap divided by the total estimated market cap of matched S&P 500 members for the month. This is not an official float-adjusted S&P index weight.