$2M Portfolio, $2M Home: A Case Study in Three Financing Paths

The cleanest way to understand the trade-offs between cash, mortgage, and SBLOC for a home purchase is to work a specific example end-to-end. This post walks through a case study with a simple setup: a buyer with a $2M taxable portfolio looking at a $2M home. One-to-one ratio, significant gains, mid-career tax bracket.

I pick this ratio because it is the classic HNW home purchase scenario and because it produces outcomes that surprise most borrowers. With a bigger portfolio relative to the home, the SBLOC dominates easily. With a smaller portfolio, the cash option stops being feasible. At 1:1, the three paths are close enough that the differences reveal which variables actually matter.

The Setup

Meet our case-study buyer:

• Age 42, dual-income household, high-earners in a HCOL metro.
• Taxable portfolio: $2,000,000, diversified in US index funds.
• Cost basis: 50% — so $1M in unrealized long-term capital gains.
• Combined marginal tax rate on long-term gains: 23.8% federal (20% + 3.8% NIIT) + 9% state = 32.8%.
• Household income: $600K/year.
• Home purchase price: $2,000,000.
• Time horizon: plan to own the home 10+ years, portfolio growing at expected 7% real return over the same period.
• Mortgage rate available: 6.75% on a 30-year jumbo.
• SBLOC rate available: 6.25% at a relationship banker.

I will model each path over 10 years of holding, then total the all-in after-tax cost.

Path A: All Cash, Liquidate Portfolio

Buyer sells $2M of the portfolio, pays capital gains tax, uses the rest plus other liquidity to cover the home.

First, the tax hit on the sale:

• Unrealized gain on the sold portion: $1,000,000 (the whole gain is realized because we're selling 100%).
• Federal capital gains tax: $1,000,000 × 23.8% = $238,000.
• State capital gains tax: $1,000,000 × 9% = $90,000.
• Total tax: $328,000.

Net proceeds: $2,000,000 − $328,000 = $1,672,000. Not enough to buy the $2M home outright. Buyer needs $328,000 of additional cash from salary savings or other sources to complete the purchase.

Ten-year position:

• Home equity: $2,000,000 (assuming flat home price for simplicity; appreciation is the same across all paths so it cancels out).
• Portfolio: $0 (fully liquidated).
• Total wealth: $2,000,000.

Compared to the starting wealth of $4,000,000 in assets ($2M portfolio + $2M eventually committed to the home), the cash path leaves the buyer in a materially worse position because:

1. The $328K tax hit is a permanent loss.
2. The $2M portfolio's growth over 10 years is forgone. At 7%/year, that is $2,000,000 × (1.07^10 − 1) = $1,933,000 of lost compounding.
3. The buyer has no liquid wealth after purchase; all $2M is in home equity.

Total cost of cash path, over 10 years: $328,000 in taxes + $1,933,000 in forgone compounding = $2,261,000 on an after-tax, opportunity-cost basis.

Path B: Jumbo Mortgage, $400K Down, Liquidate Partial

Buyer puts 20% down ($400K) and finances $1.6M on a 30-year jumbo at 6.75%. The $400K down payment comes from liquidating portfolio assets.

Tax hit on the partial sale:

• Portion liquidated: $400K of market value.
• Gain on liquidated portion: $400K × 50% = $200K.
• Federal tax: $200K × 23.8% = $47,600.
• State tax: $200K × 9% = $18,000.
• Total tax: $65,600.

Net proceeds after tax: $400K − $65,600 = $334,400 — not enough to cover the $400K down payment. Buyer must contribute an additional $65,600 from salary savings.

Mortgage math:

• Mortgage balance: $1,600,000 at 6.75% over 30 years.
• Monthly P&I: $10,373.
• Over 10 years: $1,244,760 paid, of which $1,012,000 is interest and $232,760 is principal reduction.
• Balance after 10 years: $1,367,240.

Interest deduction value:

• The mortgage is secured by a qualified primary residence.
• Federal law caps the deduction at interest on $750K of acquisition indebtedness.
• Roughly 750/1,600 = 46.9% of the interest paid is deductible in early years.
• Assume deductibility fraction drops to about 40% on average over 10 years as principal is paid down.
• Federal tax savings on deductible interest: $1,012,000 × 40% × 37% = $149,776.
• State tax may also apply (California allows higher cap; NY caps lower). Assume state savings of $1,012,000 × 40% × 9% = $36,432.
• Total deduction value: $186,208.

Remaining portfolio: $2,000,000 − $400,000 = $1,600,000, growing at 7% for 10 years = $3,148,000.

Ten-year position:

• Home equity: $2,000,000 − $1,367,240 = $632,760.
• Portfolio: $3,148,000.
• Total wealth: $3,780,760.
• Lifetime out-of-pocket: $65,600 (taxes) + $1,012,000 (interest) − $186,208 (deduction value) = $891,392.

Total cost of mortgage path: $891,392 on a net-of-deduction basis.

Path C: SBLOC, $2M Drawn, No Liquidation

Buyer draws $2M from an SBLOC secured by the full $2M portfolio to buy the home in cash. The portfolio stays intact.

Tax hit: $0 (no liquidation).

SBLOC math:

• SBLOC balance: $2,000,000 at 6.25%.
• Annual interest: $125,000 (interest-only).
• Over 10 years: $1,250,000 in cumulative interest.

Initial LTV: $2M loan / $2M portfolio = 100%. This is way over the typical 50% initial LTV cap. The buyer CANNOT actually execute this trade — there is not enough collateral.

Adjusted setup: buyer uses a 50/50 mix — $1M SBLOC (at 50% of the $2M portfolio, which is roughly the max initial LTV) plus $1M mortgage at 6.75%.

Revised Path C: SBLOC + Smaller Mortgage, Zero Liquidation:

• SBLOC: $1,000,000 at 6.25%. Annual interest: $62,500. Over 10 years: $625,000.
• Mortgage: $1,000,000 at 6.75% on 30-year jumbo. Monthly P&I: $6,483. Over 10 years: $777,960 paid, of which $641,000 is interest and $136,960 is principal reduction. Balance after 10 years: $863,040.
• Mortgage deduction value: $750K cap cleanly covers full balance. Deductibility ~100% of interest. Federal savings: $641,000 × 37% = $237,170. State savings: $641,000 × 9% = $57,690. Total deduction value: $294,860.
• SBLOC interest: not deductible by default. Full $625,000 cost, no offset.
• Portfolio: $2,000,000 grows at 7% for 10 years = $3,934,000. (Not reduced because nothing was liquidated; the SBLOC borrows against it but does not sell.)

Ten-year position:

• Home equity: $2,000,000 − $863,040 (mortgage balance) = $1,136,960.
• Portfolio: $3,934,000.
• SBLOC balance owed: $1,000,000 (assuming interest-only service).
• Total net wealth: $1,136,960 + $3,934,000 − $1,000,000 = $4,070,960.

Lifetime out-of-pocket cost: $625,000 (SBLOC interest) + $641,000 (mortgage interest) − $294,860 (mortgage deduction value) = $971,140.

The Comparison

Path	10-Yr Cost	Ending Net Wealth	Notes
A: All Cash	$2,261,000	$2,000,000	Worst. Tax hit plus all opportunity cost.
B: Jumbo Mortgage	$891,392	$3,780,760	Best on cost, near-best on wealth.
C: SBLOC + Smaller Mortgage	$971,140	$4,070,960	Highest ending wealth, second on cost.

A few observations that surprise most readers:

The all-cash path is the clear loser by a wide margin. $2.26M in effective cost on a $2M home, once you price in taxes and forgone compounding, is enormous. This is the scenario most "simple" buyers intuitively prefer and it is the one that punishes them the hardest.

Path B (mortgage) has a slightly lower dollar cost than Path C (SBLOC + mortgage). The mortgage interest deduction is doing a lot of work here. Path B is cheaper on nominal out-of-pocket cost by about $80K over ten years.

Path C has higher ending wealth despite the higher cost. The intact $2M portfolio compounds harder than the interest cost. After ten years, the SBLOC path leaves the buyer roughly $290K richer even though they spent $80K more on financing. The delta is the value of the bigger portfolio base.

The SBLOC path's advantage grows with time. At 10 years, Path C is only $290K ahead. At 20 years, the compounding gap is closer to $1.5M. The longer the hold, the more valuable the SBLOC's non-liquidation feature becomes.

Which Path Is Right?

The right answer depends on which variable the buyer cares most about.

If the goal is minimum nominal cost of the home purchase itself, Path B wins. The mortgage is cheap money after the deduction, and the partial liquidation is small enough to absorb.

If the goal is maximum long-term wealth, Path C wins. The bigger portfolio base produces a bigger compounded outcome, and the extra interest cost is a reasonable price for that outcome.

If the goal is zero debt and simplicity, Path A wins — but at an enormous hidden cost. Most advisors would argue the simplicity premium is not worth $1.3M over the better paths.

The buyer's risk tolerance also matters. Path C adds an SBLOC on top of a mortgage, which means two concurrent liabilities. If the market draws down and the buyer has to service both — the mortgage from salary and the SBLOC from portfolio — the stress is real.

The Real Variable: What the Portfolio Returns

Every number above assumes a 7% portfolio return. If you change that assumption, the paths re-rank.

At 4% portfolio return: Path B wins on both cost and wealth. The SBLOC's interest cost exceeds the portfolio's growth, so the leverage is a drag.

At 7% portfolio return: Path C wins on wealth, Path B wins on cost, but they are close enough to be a judgment call.

At 10% portfolio return: Path C wins on both cost and wealth. The portfolio crushes the leverage cost, and the ending wealth gap widens to $1M+ over ten years.

The single biggest assumption in any HNW financing decision is the expected portfolio return. If you are confident your portfolio will outearn the SBLOC rate by 2%+ annually, the SBLOC wins. If you are not confident, the mortgage is the safer bet.

Run Your Own Numbers

This case study uses round numbers and a specific tax profile. Your situation will differ: different cost basis, different state, different mortgage rate available to you, different expected returns.

Stockstead runs exactly this analysis against your actual numbers. Plug in your portfolio, your cost basis, your tax bracket, your expected returns, and the rates quoted to you. See all three paths with the real trade-offs side-by-side.

Compare Your Options with Stockstead →

A 1:1 portfolio-to-home ratio is the HNW sweet spot. Choosing the wrong path at this scale is a $1M+ mistake. Choosing the right one compounds over decades.