Demographics tell you the demand side of a market. Absorption, vacancy, and rent trends tell you the supply side — and the interaction between the two is what actually moves prices.

A market with strong demand but oversupply will see flat or falling rents. A market with weak demand and constrained supply can still see rising rents. The arithmetic of supply and demand is what you're solving for in market analysis, and these three metrics are the variables.

Absorption — the demand pulse

Absorption = the change in occupied space (in units or square feet) over a given period.

It's the direct measure of "how much new space did the market actually consume?" If 1,000 multifamily units became newly occupied this year, absorption was 1,000 units. If 500 units became occupied while 200 became vacant (move-outs net of move-ins), net absorption was 300 units.

There are two flavors:

Gross absorption

Total leased volume — every new lease signed during the period. Includes tenants who moved from one space to another within the market. Useful for measuring market activity, less useful for measuring net demand.

Net absorption

Change in total occupied space. (Move-ins minus move-outs.) This is the number you want — it tells you whether the market is actually growing or just churning.

Example. A submarket has 10,000 multifamily units. At the start of the year, 9,200 are occupied (92% occupancy). At the end of the year, 9,300 are occupied (93%). Net absorption = 100 units for the year.

Why absorption matters

Absorption is the demand side of the supply-demand equation. Compare absorption to new deliveries:

If absorption > new deliveries → vacancy falls, rents rise
If absorption ≈ new deliveries → vacancy flat, rents rise modestly with inflation
If absorption < new deliveries → vacancy rises, rents flatten or fall

This is the core supply-demand arithmetic of CRE. It's simple, but most investors don't actually run it. They look at vacancy in isolation ("oh vacancy is 5%, that's healthy") without checking whether the trend is improving or deteriorating.

Vacancy — the inventory level

Vacancy rate = % of total inventory that's currently unoccupied.

Where to find it:

CoStar (gold standard, granular by submarket and property type)
Reis / Moody's CRE
Yardi / RealPage for multifamily
Local appraisal reports
Brokerage market reports (CBRE, JLL, Colliers, Cushman publish quarterly free)
Federal Reserve Bank district reports for general direction

What's "healthy"? It varies by asset class:

| Asset class | Healthy vacancy | Tight market | Oversupplied | |---|---|---|---| | Class A multifamily | 5-7% | < 4% | > 8% | | Class B/C multifamily | 5-8% | < 5% | > 10% | | Stabilized retail | 5-9% | < 6% | > 12% | | Office | 8-14% | < 10% | > 18% | | Industrial / warehouse | 4-7% | < 3% | > 10% | | Self-storage | 8-12% | < 8% | > 15% |

A "tight market" is one where landlords have pricing power and rents are growing fast. An "oversupplied market" is one where landlords are offering concessions and rents are stagnant or falling.

But the trend matters more than the level. A 7% vacancy market with vacancy falling fast is different from a 7% vacancy market with vacancy rising fast. The first is improving; the second is deteriorating.

Rent trends — the price signal

Asking rent — what landlords are listing units at right now Effective rent — what tenants are actually paying after concessions (free months, TI, lease incentives)

In a tight market, asking ≈ effective. In a soft market, the gap widens — effective rents are 5-15% below asking because of free months, lease-term flexibility, and TI giveaways.

When you read "rents grew 4% last year" in a market report, ask: was that asking rent or effective rent? In 2024-2025, many Sunbelt multifamily markets had rising asking rents but flat-to-falling effective rents because concessions were back. That's a market in trouble, not a market growing.

Year-over-year vs. rolling

Y/Y rent growth — most recent month vs. same month prior year. Easy to find but volatile.
Trailing 12-month rent growth — average of last 12 months vs. prior 12. Smoother, more reliable.
Quarter-over-quarter (QoQ) — 3-month moving average. Best for spotting inflection points.

When a market is rolling over (turning from growth to flat), QoQ goes negative first, then trailing 12-month, then Y/Y. By the time Y/Y rent growth turns negative, the market has been in trouble for 9-12 months.

The supply pipeline

Equally important: how much new supply is in the construction pipeline?

Sources:

CoStar / Yardi for granular pipeline tracking
Local building permit data (Census)
Trade press announcements

What to look for:

Under construction as % of total inventory. Above 5%/year is heavy supply; above 10% is a wave that will pressure rents.
Completion timeline — when will the new supply hit? A wave delivering in 12 months pressures rents in 12 months.
Geographic concentration — is supply concentrated in your specific submarket or spread evenly?

Example. A submarket with 12,000 multifamily units has 1,800 units under construction (15% of inventory). That's a massive supply wave. Even if demand is strong, the next 18-24 months will see rising vacancy and concessions return as new product lease-up competes with existing inventory.

The same submarket with only 200 units under construction (1.7% of inventory) is supply-constrained. Demand has nowhere to go but bid up the existing units.

The supply-demand math worked example

Here's how to put it together for a submarket. Assume Lake Nona, FL multifamily:

Current inventory: 8,500 units
Current occupancy: 95%
Trailing 12-month absorption: +600 units
Under construction: 1,200 units
Expected delivery: 800 in next 12 months, 400 in months 13-24
Job growth (MSA): 2% (~30,000 new jobs)
Multifamily share of housing demand: ~35% (rough rule of thumb)
Estimated new MF demand from job growth: ~1,500 households over 24 months

Supply over next 24 months: 1,200 units Demand over next 24 months: ~1,500 units (slightly conservative)

Demand exceeds supply slightly. Rents continue to rise modestly (2-4%/year), vacancy stays tight (5-7%). This is a healthy steady-state market — not a boom, but no collapse risk.

Now compare to a submarket with 8,500 units, 1,200 absorption, but 2,500 units under construction:

Supply over next 24 months: 2,500 units Demand over next 24 months: ~1,500 units

Supply exceeds demand by 1,000 units. Vacancy will rise from 5% to ~12% as the new product lease-up. Rents flat or falling. Concessions return. Anyone buying at today's cap rate will see their pro forma break.

This is exactly what happened in Phoenix and parts of Austin in 2023-2024. The investors who modeled supply explicitly avoided it. The investors who just looked at "5% vacancy, healthy market" walked into the buzzsaw.

Where to find absorption and rent trend data

Free / cheap:

Major brokerage market reports — CBRE, JLL, Colliers, Cushman, and Marcus & Millichap all publish free quarterly market reports for major MSAs. They include vacancy, rent growth, absorption, and supply pipeline data. Search "[MSA name] multifamily market report Q[X] [year]" — you'll find them.
Federal Reserve Bank district reports — Atlanta Fed, Dallas Fed, etc. publish "Beige Book" qualitative reports plus periodic CRE-specific surveys.
Apartments.com / RentCafé / Zumper — free aggregated rent data at the city and ZIP level. Less reliable than CoStar but free.
Local economic development organizations — many publish quarterly market overviews with absorption data.

Paid:

CoStar — the standard. Granular by submarket, property type, vintage, and class. $5K-$30K/year depending on subscription tier.
Yardi Matrix — multifamily-focused, slightly cheaper than CoStar.
Reis / Moody's CRE — submarket data on multiple property types.

For most beginners, the brokerage reports + RentCafé are sufficient. Add CoStar when you're doing 5+ deals/year and have $10K+ in deal income to justify the cost.

Spotting an inflection point

The hardest skill in market analysis is identifying when a market is about to turn — from growth to top, or from bottom to recovery. Three signals:

Signal 1: Construction pipeline accelerating while absorption flatlines

Permits up, deliveries up, but absorption can't keep pace. This is the textbook setup for vacancy increases and rent decline. Watch the pipeline-to-absorption ratio. When pipeline is more than 1.5x trailing absorption, supply is overshooting.

Signal 2: Concessions returning

When you see "1 month free" or "$500 move-in credit" on listings in a market that hadn't been offering concessions, that's the first warning. Effective rents are falling even though asking rents look fine.

Signal 3: Days-on-market lengthening

Time to lease creeping up — 30 days becomes 45 becomes 60. This is the demand side weakening. Listings sitting longer means tenants have more choices.

When 2 of these 3 signals appear, the market has rolled over even if rent growth is still positive. Adjust your underwriting to flat-to-down rent growth and 1-2 percentage points higher exit cap.

Bottom indicators (the upside)

The reverse signals tell you a market is bottoming and about to recover:

Construction starts have collapsed (no new supply for 18-24 months)
Concessions have peaked and are starting to shrink
Population/job data starts turning up before any official market reports

Buying near a market bottom is the highest-return moment in real estate. The signal usually comes 6-12 months before the trade press catches on.

What to take away

Absorption = change in occupied space; net absorption is the demand pulse
Compare absorption to new deliveries to predict vacancy direction
Track effective rent, not asking rent — concessions hide weakness
Watch under-construction as % of inventory; >5%/year is heavy supply
Brokerage reports + RentCafé are good free starting points; CoStar for serious work
Three rollover signals: pipeline > absorption, concessions returning, longer days-on-market
Three bottom signals: starts collapsed, concessions peaked, leading indicators turning up

Next lesson: traffic counts, daytime population, and the location data that drives retail underwriting — the metrics that don't apply to multifamily but are make-or-break for retail and QSR.

Absorption, Vacancy, and Rent Trends — Reading the Supply Side