IRON MOUNTAIN INC vs SIMON PROPERTY GROUP, INC., two REIT stocks. A side-by-side on valuation, growth, margins, returns, and what each price is betting.
Simon Property is a mature mall landlord returning cash; Iron Mountain is a storage company spending it to become a data-center player, and the two could hardly want different things from a dollar of rent. Simon yields 3.77% and generates 4.38% free cash from Class-A malls; Iron Mountain yields 2.43% but runs free cash negative at 1.6% as capacity spending outruns its storage income. Simon's 15.8 P/E is the sector's most cautious, Iron Mountain's 144 among its most inflated, though both distort through REIT depreciation. Simon carries mall leverage at 4.65 turns, Iron Mountain its own heavy load. The pair prices a cash-returning retail landlord against a cash-consuming transformation: Simon harvests premium malls it already owns, Iron Mountain funds the data centers it hopes to grow into, one paying out, the other building out.
Comparison updated 2026-07-11.
| Metric | IRM | SPG |
|---|---|---|
| Price | $132.50 | $226.89 |
| Market cap | $39.6B | $73.7B |
| Sector | REIT | REIT |
| Stage | Growth | Mature |
| P/E | 144.0 | 15.8 |
| P/B | — | 12.14 |
| P/S | 5.46 | 11.09 |
| EV/EBITDA | 24.0 | 21.3 |
| Revenue growth | +15.6% | +10.9% |
| Operating margin | 20.4% | 43.4% |
| Net margin | 3.9% | 82.0% |
| Return on equity | — | 89.8% |
| Return on assets | 1.3% | 13.8% |
| Return on invested capital | 6.8% | 7.4% |
| FCF yield | -1.6% | 4.4% |
| Dividend yield | 2.4% | 3.8% |
| Debt / equity | — | 4.65 |
| Current ratio | 0.77 | — |
| Altman Z (solvency) | 6.36 | 1.39 |
| Piotroski F (quality) | 6 / 9 | 8 / 9 |
Each week boothcheck ranks the stocks whose prices are betting on the most. Read the most stretched bets archive →
boothcheck is also on Android. Get the app on Google Play →
The stronger value is highlighted per metric where one is strictly better on that single number; it is not an overall verdict on either company. For informational and research purposes only. Not investment advice. Not a recommendation to buy, sell, or hold any security. boothcheck is not a registered investment adviser. Past performance does not guarantee future results.