An Amazon engineer stopped sitting on $400K of company stock and finally slept.

How an Amazon SDE cut her company stock concentration from 41% to 18% - and avoided $13,800 in IRS underpayment penalties in the process.

The Situation

Aisha is 34 and has spent six years at Amazon as a Senior SDE. Between base salary and RSU vesting, she's been clearing around $380,000 a year - and on paper, everything looked fine. She maxed her 401k every year, kept a healthy emergency fund, and never missed a vest window. She was doing everything she was supposed to do.

But as layoff headlines started cycling through her linkedin feed in early 2026 -Amazon had already cut thousands of roles - she did the math on her actual financial picture for the first time. The number that stopped her: Amazon stock made up 41% of her total investable assets. Five different vest cohorts, five different cost bases, no coordination between any of them. Her CPA filed accurate returns every April. Her brokerage showed a growing position. But those two worlds had never spoken to each other.

The Gap We Found

Amazon's default supplemental withholding on RSU income is 22%. Aisha's marginal federal rate was 37%. Every single vest had quietly created an underpayment gap, and no one had flagged it, not her payroll system, not her CPA, and not the brokerage that held the shares. The larger issue, though, was structural: no one was looking at her Amazon concentration in the context of her total financial picture. Holding 41% of your net worth in a single employer, especially one making headlines for workforce reductions, isn't a tax problem. It's a risk management problem that also has a tax problem hiding inside it.

What We Did

The first step was establishing a sell-at-vest policy going forward: every new lot of shares that vests gets sold immediately. This eliminates additional capital gains on future vests (selling at the same price you're taxed on means $0 incremental gain) and starts redirecting that capital into a diversified direct index portfolio, a strategy that mirrors broad market exposure across individual holdings, which lets us harvest tax losses along the way to offset gains elsewhere.

For the existing Amazon position, we used specific lot identification to pull forward the shares that had already crossed the one-year holding threshold and sell those first, capturing long-term capital gains rates rather than ordinary income rates. We didn't sell everything at once, the goal was a steady, tax-efficient reduction over 18 months rather than a single triggering event.

On the tax side, Alphanso's AI agents now parse Aisha's payroll data in real time, calculate the gap between taxes withheld and taxes actually owed, and send her a calculated quarterly estimated payment amount before each deadline. She doesn't need to remember a due date or run the math. The number shows up in her inbox.

The Result

$13,800 avoided in IRS underpayment penalties across two vesting years
Amazon concentration dropped from 41% to 18% of her portfolio over 18 months
$0 in additional capital gains on all new vest lots sold at vesting
One integrated plan - investments, estimated taxes, and a diversification roadmap, working together for the first time

Why This Worked

Aisha wasn't doing anything wrong. She was doing exactly what most Amazon engineers do: vest, hold, optimize the 401k, trust the system. The gap wasn't a bad decision, it was the absence of someone looking at the full picture all at once. Alphanso sits at the intersection of payroll data, the taxable investment account, and the tax return. That's where the real opportunities show up. Flat-fee advisory, no AUM percentage, no incentive to recommend any particular product. If you're sitting on a growing stack of company stock and aren't sure what your actual tax exposure looks like heading into Q2, it's worth a conversation.

This case study is a composite illustration based on real Alphanso client scenarios. Names and identifying details have been changed for privacy. Results are not guaranteed and will vary based on individual circumstances. All investing involves risk, including the possible loss of principal. Alphanso LLC is a registered investment adviser.