Both Sides of the Discount Moved.
A finding from the Storage Price Observatory. The Public Storage series is continuous from 29 April 2026; the six other collections were added during September 2026. Through 25 August that Public Storage collection was published as a directory called FindStorage — a product since retired, whose headline figures are frozen at that date and reported separately from the figures here.
A percentage-off advertisement contains two numbers: the stated discount and the baseline rate used to calculate savings. When daily snapshots followed exact listings through time, both numbers moved together: reference rates rose by a median of $45 on the same day "40% off" discounts appeared, and when rates were later cut, roughly half the promotional value was withdrawn alongside them — leaving modeled four-month cost slightly higher than before.
The Control That Rules Out a System Glitch
Could a website update engine simply bundle rate and promo updates together? July supplies the empirical control. Four days before August 1, hundreds of listings rotated into the same discount with zero rate hikes.
428 listings entered "40% off For 4 Months". Rates remained completely flat. Proves rate and promo fields are independently writable.
Every single listing entering the 4-month promo had its reference rate increased on the exact same morning. Median hike: +$45.
Measured on that same 4,904-offer event cohort, headline value rose 35.3% and promotional value rose 216.4%, producing a 2.1% reduction in aggregate modeled four-month cost — though the median offer cost $2 more, 55.8% of listings cost more over four months, and 96% cost more by month eight.
Anatomy of an Advertised "Savings" Figure
Tracking Costa Mesa facility #235 (Unit 5x15) through daily snapshots shows the reference rate elevated on 22 and 24 August and back down on the 25th — with the "$380 Savings" claim calculated against it on the 24th.
What the Customer Saw on Screen
The figure is exactly four months at 40% off the displayed reference rate: 4 × ($237 − $142.20) = $379.20.
The arithmetic is correct only if you accept that the unit actually cost $237.
What the Longitudinal Pipeline Caught
80.2% of the advertised savings figure rests on the elevated reference rate rather than on any change in what the unit cost on the days either side of it.
The "Rate Cut" That Quietly Raised Consumer Costs
On September 14, headline rates fell across the portfolio — no announcement was made; the change was observed in the daily snapshot. Across 59,045 exact-matched modelable listings, rates fell 14.7%. At the same time roughly half the promotional value was withdrawn, leaving modeled four-month cost on matched offers slightly higher than before.
Shapley decomposition of the 14 September reset:Looking at headline rates alone describes a customer windfall. Looking at both fields together describes something else: the rate reduction and the promotional withdrawal are close to the same size, and they point in opposite directions.
The Reset Walkback: Caught Live 96 Hours Later
Had our study frozen on September 14, it would have claimed Public Storage locked in a 25% lower rate regime entering Q4. The daily pipeline stayed online. On 18 September 2026, Public Storage logged an average price restoration of roughly +12% (panel mean; the median-of-ratios index returned to 0.9800), with 22,772 SKUs repriced (18,828 up, 3,944 down) and 17,935 promotions rewritten.
The Pre-Registered Prediction (Sealed 15 September 2026)
Public Storage reports Q3 in late October. The three predictions below were sealed in commit 2026-09-15-q3-prediction-and-ledger-gap.md before results exist.
Q3 Promotional Discounts Given
Q2 2026 reported promo discounts up 16.1% YoY. Following summer discounting and the September contraction:
Q3 New-Customer Contract Rates
Q2 reported new contract rates up 1.6% YoY (first positive reading since 2021). Weighting pre vs post reset days:
Q4 New-Customer Contract Rates
Management guided move-in rents to positive low single digits. Our daily volatility and demand models indicate:
The Heavy Lifting Lives in the Live Engine
This teardown summarizes the core findings. For the complete mathematical proofs, raw accounting tables, and national market coverage, dive straight into the rate monitor:
Full Methodology & 59k-Offer Accounting
The rigorous academic writeup with complete before-and-after tables, Shapley decomposition arithmetic, and multi-unit Costa Mesa verification.
- 59,045 matched listings in the four-month accounting ledger ($32.78M → $27.96M headline, $10.20M → $5.13M promo)
- Daily since 9 July 2026, with zero synthetic interpolation — one unexplained gap, and a deliberate five-day pause (26–30 August) taken to review changed site terms. The live count is on the dashboard.
- Full multi-unit breakdown for 5×5, 5×10, and 5×15 SKUs
- Legal boundary note and analytical portfolio methodology
7-Supplier National Rate Monitor
Interactive GIS mapping and market intelligence across 9,077 facilities and 129,704 daily SKUs from America's top storage operators (as of 15 September 2026).
- Interactive Leaflet Map: store-level inventory & rate curves
- 7-Collection Benchmark: Public Storage, U-Haul, CubeSmart, Storage Sense, SmartStop, StorageMart, and an independent-operator pilot
- Unit Size Pricing: 5×5 to 10×30 medians and interquartile ranges
- Live Movers Feed: daily price hikes and cuts logged nationally