MOBIX LABS, INC Files S-1: RSU & Capital Gains Tax Exposure Calculator (Aug 29, 2026)

What Changed

Mobix Labs filed its S-1 registration statement with the SEC on August 28, 2026. The 18 MB filing signals an impending IPO for the connectivity and wireless technology firm. For high-net-worth individuals holding pre-IPO equity or evaluating IPO allocation opportunities, this filing starts a 60 to 90 day clock to liquidity and triggers immediate tax and portfolio positioning decisions.

The Numbers That Matter

Metric	Pre-IPO (Private)	Post-IPO (Public)	Your Action Window
Liquidity timeline	No market exit	180-day lockup, then liquid	60 to 90 days until pricing
Tax treatment (equity comp)	AMT on exercise	Ordinary income at vest, capital gains at sale	Review exercise strategy now
Volatility expectation	N/A	First-day pop: 15% to 40% median (2025 data)	Set limit orders pre-open
Allocation availability	Accredited investor only	Retail access at open	Institutional clients get priority

What This Means for Your Portfolio

If you hold Mobix Labs equity as an employee or early investor, your $500K position becomes tradable in Q4 2026, subject to lockup. A $500K pre-IPO stake at a $1.2B valuation that prices at $1.8B generates $250K in unrealized gain. At the 37% federal rate plus 3.8% NIIT and state, your tax liability on a full sale would total approximately $102K, leaving net proceeds of roughly $648K after tax on the entire $750K proceeds (original capital plus gain). If you exercised ISOs in 2024 or 2025, your AMT credit carries forward and reduces your 2027 tax bill by $40K to $80K on a $500K position, depending on your exercise price and timing.

Scenario Analysis

Position Size	IPO Valuation Gain (assumes 50% step-up)	Tax on Sale (40.8% blended rate)	Net After-Tax Proceeds	Available Paths
$500K	$250K	$102K	$648K	Selling at lockup triggers the tax shown; holding longer shifts treatment toward LTCG
$1M	$500K	$204K	$1.296M	A 30% to 50% reduction within 12 months is one common concentration-management pattern
$2M	$1M	$408K	$2.592M	A partial exit at lockup with the balance held is one pattern that pairs realized gains with future tax-loss harvesting flexibility

Frequently Asked Questions

Q: When does the 180-day lockup expire for Mobix Labs insiders? A: Lockup typically expires 180 days post-IPO, landing in Q1 2027 if the company prices in Q4 2026.

Q: How much first-day volatility should I expect? A: Median first-day IPO return was 23% in 2025 for tech issuers under $2B valuation, with a range of negative 8% to positive 67%.

Q: Does selling at IPO trigger short-term or long-term capital gains? A: Short-term at 37% federal if you exercised or acquired equity less than 12 months before sale, long-term at 20% plus 3.8% NIIT if over 12 months.

Q: What determines the tax outcome of exercising remaining ISOs before the IPO prices? A: Two factors: whether the resulting AMT liability stays under $50K, and whether there is a 12-month holding window remaining for LTCG treatment. Without both, the spread at vest faces higher tax rates.

Q: What is the risk of holding through lockup expiration? A: Lockup expiration typically drops share price 4% to 12% as insiders sell, but holding to month 13 converts your gain to LTCG and saves 17 percentage points in federal tax.

Q: How do I model my exact tax liability on a Mobix Labs position? A: Your tax depends on grant date, exercise date, sale date, and whether your equity is ISO, NSO, or restricted stock, each with different ordinary income and capital gains splits.

Q: Can I offset IPO gains with tax-loss harvesting in the same year? A: Yes, capital losses offset capital gains dollar-for-dollar, and up to $3K of net capital loss per year can offset ordinary income.

Q: What portion of my portfolio should a single IPO position represent? A: A common concentration guideline caps a single stock at 10% to 15% of liquid net worth after the lockup expires, meaning a $1M position would fall within that range against $7M to $10M in total investable assets. Individual risk tolerance varies.

Run the Numbers

Use CalcMoney's Calculate Your After-Tax RSU Proceeds to model your exact tax liability and net proceeds across exercise scenarios, sale timing, and AMT carryforward before the lockup expires.

Disclaimer: This article is for informational purposes only and should not be construed as financial, tax, or legal advice. Consult a qualified financial advisor, tax professional, or attorney before making investment or tax decisions based on your individual circumstances.

Run the Numbers: Capital Gains Tax Terminal on CalcMoney — see your exact figures under current market conditions.

Data sourced from SEC EDGAR S-1 Filings (IPO). Rates and thresholds are for informational purposes only. Consult a licensed financial advisor before making mortgage, investment, or tax decisions.

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