Fixed Costs, Fragile Edges: A UK Deal-Level Audit of the PTM Levy and Administrative Drag

UK equity dealing is rarely priced in one number. A contract note may show commission, stamp duty or SDRT, and the spread is visible on screen, but the true fixed-cost burden is scattered across small line items. At Sapphire Traders, the working assumption is that strategy should not be dictated by pennies; nevertheless, pennies that recur can quietly change the economics of a trading plan. In 2026, the PTM Levy remains a familiar example: £1 on purchases and sales of relevant UK, Channel Islands and Isle of Man shares where consideration exceeds £10,000. It is not a tax, but a statutory levy collected by brokers for the Panel on Takeovers and Mergers. On its own it is trivial. Inside a high-turnover process, it is one entry in a ledger that deserves an audit.

Where the small charges actually sit

The first task is to separate statutory costs from broker costs and from implicit execution costs. The PTM Levy sits in the statutory bucket, alongside stamp duty reserve tax at 0.5 per cent on electronic purchases of most UK-incorporated shares. Sales do not attract SDRT, but they can still attract the PTM Levy where the consideration exceeds £10,000. AIM shares are generally outside the SDRT net, yet that does not make every AIM bargain free of levies or broker charges.

The broker bucket is broader than many traders assume. Dealing commission is the obvious item, but platform fees, telephone-dealing surcharges, non-sterling FX conversion spreads, corporate-action handling fees, paper-statement charges, inactivity fees and withdrawal fees all belong in the same review. Some are fixed per ticket; some are fixed per year; some are proportional. The implicit bucket includes the bid-offer spread and market impact. These are not printed as a single charge, but they are real costs of execution and should be measured alongside the visible ones.

The arithmetic of frequency

A single £1 levy looks harmless. The problem is repetition. Consider a £12,000 UK share purchase and later sale through a broker charging £4.95 per deal. The round trip carries £9.90 in commission and £2 in PTM Levy, or £11.90 in fixed charges. That is roughly 10 basis points of the £12,000 position. Add 0.5 per cent SDRT on the purchase, or 50 basis points, plus an assumed 12 basis points of spread cost, and the round-trip burden is closer to 72 basis points before any market impact.

For a trader running 20 such round trips a year, the executed turnover is £240,000. Fixed charges alone reach £238, before SDRT and spread. The individual £1 entries are not the story; the story is that a strategy needs to clear a higher hurdle each time it trades. A short-term edge of 40 basis points per idea may look attractive in isolation, but it can disappear once the full cost stack is applied.

Small positions are more exposed. A £2,500 trade may fall below the PTM Levy threshold, but £4.95 commission each way is already about 40 basis points of the position. Add SDRT at 50 basis points on the purchase and a 15 basis point spread, and the round-trip cost can exceed 100 basis points. The absence of a £1 levy is little comfort when the fixed ticket charge is doing most of the damage.

Why the levy threshold changes behaviour

The £10,000 threshold creates a visible boundary. A bargain just above it attracts £1; a bargain just below it does not. In theory, a trader could shave size to avoid the levy. In practice, that is usually poor discipline. A £1 saving is one basis point on a £10,000 trade, and distorting position size to capture it can create unintended exposure or leave a strategy under-hedged. The levy should be recorded and understood, not used as a reason to bend a sizing rule.

The more useful lesson is that fixed costs make trade count a risk variable. Two traders can hold the same view, use the same broker and trade the same shares, yet end up with different net results because one turns the book over more often. Micro-costs do not argue for inertia; they argue for selectivity. Every additional bargain must justify its own administrative drag.

A practical audit checklist

Begin with evidence rather than memory. Pull 12 months of contract notes, platform statements and cash statements. Build a simple ledger with four columns: date, executed value, charge type and amount. Tag each charge as statutory, broker ticket, platform, FX or ancillary. Then convert the totals into basis points of executed value and into a percentage of average portfolio value.

Next, calculate the fixed-cost break-even for a typical position. Divide the round-trip fixed charges by the position value, then compare the result with the expected edge. If the fixed charge consumes more than a quarter of the anticipated gross edge, the trade deserves a second look. Review the average ticket size and the number of tickets. A high number of small tickets is usually a sign that commission and administration are being spread too thinly.

Reconcile the PTM Levy explicitly. Count the chargeable bargains above £10,000 and confirm that the levy appears on both purchases and sales where applicable. Check whether any platform or ancillary fees can be removed without harming execution quality. Paper statements, telephone dealing and avoidable FX conversions are common sources of quiet drag. Finally, set a minimum economic position size and a maximum trade count for the strategy, then re-audit quarterly. The aim is not to eliminate every £1 charge; it is to ensure that the trading process is not funding administrative friction with genuine edge.

What to change, what not to

The sensible response to micro-costs is structural, not cosmetic. Reduce unnecessary turnover, size positions so that fixed charges are proportionate, and consolidate where consolidation does not increase execution risk. Do not abandon a valid risk rule to save a levy, and do not assume that a low-commission broker is cheap if the platform or FX charges are punitive. The contract note is a risk document as well as a receipt. Read it as one.