The Corporate Executive's Guide to Diversifying Concentrated RSU Positions

For many senior executives at FTSE-listed or major US corporations, a significant portion of their net worth is often held in employer stock. This is a natural consequence of compensation structures where Restricted Stock Units (RSUs) and share options form a substantial part of remuneration. While this aligns the interests of the executive with those of shareholders, it creates a considerable, often unacknowledged, concentration risk.

A portfolio dominated by a single stock is exposed to idiosyncratic risks unrelated to broader market movements. Company-specific events, sector-wide headwinds, or even a shift in market sentiment can lead to a material decline in wealth. The prudent course of action is diversification, a process of systematically reducing this concentration and reallocating capital across a wider range of assets.

This article provides a framework for UK-resident executives to manage this process. It examines the tax and regulatory mechanics of disposing of vested RSUs and explores strategies for reinvesting the proceeds into diversified private market assets, a growing and important part of a sophisticated investor's portfolio.

Unlike share options, a Restricted Stock Unit (RSU) is a straightforward promise from an employer to grant an employee a specific number of shares at a future date, provided certain conditions are met, typically continued employment over a vesting period. Upon vesting, the employee receives ownership of the shares.

The vesting event is the first point of taxation. At the moment the shares become yours, their market value is treated as employment income by His Majesty's Revenue and Customs (HMRC). This amount is subject to income tax through Pay As You Earn (PAYE) and, depending on your earnings, National Insurance Contributions (NICs) at the prevailing rates.

Most large employers operate an automated 'sell-to-cover' system. To settle the tax liability, a portion of the newly vested shares is immediately sold on the employee's behalf, with the proceeds remitted directly to HMRC. The remaining shares are then transferred to the executive's brokerage account. These shares now form the basis of the concentration problem, with an acquisition cost equal to their market value on the date of vesting.

Once you own the shares outright, any subsequent increase in their value is subject to Capital Gains Tax (CGT) upon disposal. The capital gain is calculated as the difference between the sale price and the acquisition cost (the market value when you received the shares).

The UK government has made significant changes to CGT allowances and rates. The annual exempt amount has been progressively reduced, meaning more of any gain is now taxable. For the 2025/2026 tax year and beyond, executives should plan for a potential blanket CGT rate of 24% on share disposals, though this is subject to final confirmation in forthcoming Budgets. Planning for a higher tax burden is the most conservative approach.

To correctly calculate the gain, UK investors must follow specific share identification rules. These include the 'same day' rule and the 'bed and breakfasting' 30-day matching rule. Beyond this, all shares of the same class in the same company are treated as a single asset, known as a Section 104 Holding. The cost of this holding is an average of the acquisition costs of all the shares within it, which is critical for calculating the precise CGT liability on a partial disposal.

UK-resident executives of US-listed companies navigate an additional layer of complexity. The primary instrument for managing this is the UK-US Double Taxation Agreement (DTAA), which prevents both countries from taxing the same income or gain. For compensation related to UK-based work, the UK generally has the primary right to tax.

Upon the vesting or sale of shares, US brokers may be required to levy a Non-Resident Alien (NRA) withholding tax, typically at 30%. By filing a Form W-8BEN with the broker, a UK resident can claim benefits under the DTAA to reduce this withholding, often to zero for capital gains and 15% for dividends.

You may also encounter references to a Section 83(b) election in US documentation. This allows employees to pay income tax on the fair market value of restricted stock when it is granted, rather than when it vests. However, this is primarily relevant for founders or early employees receiving actual restricted stock (not units) at a very low value. For typical RSU grants, which have no value until they are vested, a Section 83(b) election is not applicable.

Selling a large block of shares is not as simple as logging into a brokerage account. Senior executives are considered insiders and are subject to strict rules to prevent trading on material non-public information. Companies enforce blackout periods, typically in the weeks leading up to and immediately following quarterly earnings announcements, during which executives are prohibited from trading.

To manage this, executives at US-listed firms can use a Rule 10b5-1 plan. This is a written, pre-arranged trading plan established when the executive is not in possession of sensitive information. The plan specifies the amount, price, and dates of future sales, or delegates authority to a third-party broker to execute trades according to a set formula. Once established, trades can be executed automatically, even during blackout periods.

A 10b5-1 plan provides a strong affirmative defence against insider trading allegations. It allows for a systematic, orderly diversification process over a period of months or years. For executives at UK-only listed firms, a similar disciplined approach can be adopted through a discretionary management agreement with a broker, which sets out a clear and pre-agreed disposal strategy.

Once proceeds from share sales are realised, the question becomes how to reinvest them effectively. For investors seeking returns that are less correlated with public equity markets, private market assets offer a compelling alternative. Historically difficult to access, new fund structures are opening up this world to a wider range of investors.

The Long-Term Asset Fund (LTAF) is a new category of UK-regulated fund, authorised by the Financial Conduct Authority (FCA), specifically designed to invest in illiquid assets like private equity, private credit, and infrastructure. Major asset managers including Schroders Capital, BlackRock, and Aviva Investors have launched, or are in the process of launching, LTAFs for 2025 and 2026. These vehicles offer a regulated, diversified entry point into private markets, albeit with managed liquidity through longer redemption periods.

Another established route is via Listed Private Equity Investment Trusts. These are closed-ended investment companies traded on the London Stock Exchange, such as HgCapital Trust (HGT) or HarbourVest Global Private Equity (HVPE). They own a portfolio of private company investments but their own shares are liquid and can be traded daily. Investors should be aware that the share price of these trusts can trade at a significant premium or discount to the underlying Net Asset Value (NAV) of their investments.

Beyond direct reinvestment, sophisticated tax strategies can enhance the efficiency of a diversification programme. The Enterprise Investment Scheme (EIS) is a government programme that offers significant tax reliefs to incentivise investment in smaller, higher-risk trading companies.

A key benefit is CGT deferral relief. By reinvesting a capital gain that arises from an RSU sale into an EIS-qualifying company, the tax liability on that gain is deferred. It will not become payable until the EIS investment is sold or becomes non-qualifying. To retain this benefit, the EIS shares must be held for at least three years. This strategy can be used to postpone a large CGT bill while simultaneously gaining exposure to a portfolio of venture capital style investments.

For philanthropically inclined executives, gifting shares to a registered charity is an exceptionally powerful tax-planning tool. A gift of listed shares to charity does not create a CGT charge for the donor. Furthermore, the donor can claim income tax relief on the full market value of the gifted shares. This combination of CGT and income tax relief makes it one of the most tax-efficient ways to dispose of a concentrated holding while supporting a chosen cause.

A successful diversification strategy is not a single event but a structured, multi-year process. A robust framework can be broken down into five key stages, ideally undertaken with professional financial and tax advice.

First, Quantify and Assess. Calculate the precise percentage of your total net worth, including property and pensions, that is tied up in your employer's stock. Recognise this figure as your primary concentration risk metric.

Second, Plan Disposals. Based on your risk tolerance and financial goals, create a written plan to reduce the holding to a target level over one to three years. Where available, codify this using a Rule 10b5-1 plan or a discretionary mandate with a broker, scheduling regular sales post-vesting.

Third, Model the Financial Outcome. Work with an accountant to project the income tax and CGT liabilities for each planned disposal. This will determine the net cash available for reinvestment, avoiding any unexpected tax burdens.

Finally, Structure the Reinvestment. Define a target asset allocation for the new capital. This should be a diversified mix of public equities, fixed income, and potentially a 10-20% allocation to private markets through a blend of LTAFs and listed investment trusts to balance liquidity and return potential. Advanced tools like EIS can be layered on top for specific risk appetites and tax objectives.

Moving capital from a single-stock concentration into a diversified portfolio, including private markets, is a fundamental exercise in risk management. The objective is not to eliminate risk, but to exchange a highly concentrated, specific risk for a broad, diversified set of market risks that are more likely to deliver stable, long-term growth.

Investments in private markets carry their own considerations. Assets like those held in an LTAF are inherently illiquid, and valuations can be less frequent and more subjective than those of publicly traded securities. Fees can also be higher. However, these risks are often the source of the potential for higher returns compared to public markets.

The process of unwinding a concentrated stock position requires careful planning, discipline, and expert guidance. By using the tax, legal, and investment structures available, executives can build a more resilient financial future, independent of the fortunes of a single company.