What Is Execution Quality (and Why Your Broker's Averages Don't Tell You Enough)
Every major broker publishes execution quality statistics — the percentage of shares filled at prices better than the National Best Bid and Offer (NBBO), the average effective spread relative to the quoted spread, and similar measures. Schwab, Fidelity, Robinhood, and E*TRADE all report these numbers, usually every quarter.
The problem is what those numbers actually describe: a firm-wide average across every account, every order size, every time of day. They tell you almost nothing about whether your specific trade, placed at your specific moment, actually got a fair price. A broker can report excellent aggregate statistics while a particular fill you received was worse than the market at that instant — and you'd have no way to know, because the tools to check don't exist for individual traders.
Why This Needs a Dedicated Tool, Not Just Reading the Broker's Report
Personal Execution Quality Scorecard takes the same methodology brokers use in their aggregate disclosures — price improvement, effective spread, the effective/quoted (E/Q) ratio — and applies it to one trade at a time, using your own fill data. Instead of a firm-wide percentage buried in a quarterly PDF, you get an instant letter grade on the trade you just made.
Key Trader Pain Points and How This Extension Solves Them
| Pain Point | How the Scorecard Solves It |
|---|---|
| Brokers self-report execution quality in aggregate — there's no way to audit your own individual fills against it | Every trade you log gets its own personal comparison against the NBBO at the time you filled |
| Terms like "effective spread" and "E/Q ratio" mean nothing without a calculator translating them into dollars | Every metric is converted into a plain dollar amount and a single letter grade (A–F) |
| No easy way to compare execution quality across brokers using your own trade history | Log trades from multiple brokers and see a side-by-side breakdown of which one actually executes better for you |
| Retail traders can't tell if payment-for-order-flow routing is costing them real money, trade by trade | A running dollar total shows your cumulative price improvement or slippage across every logged trade |
| Manual NBBO lookup and comparison for a historical timestamp is tedious enough that almost nobody actually does it | Enter the numbers once and every calculation — midpoint, spread, ratio, grade — happens instantly |
How the Personal Execution Quality Scorecard Works
The core loop is the same for every trade: enter what happened, enter what the market was quoting, get an instant grade.
Step 1 — Install and Open the Scorecard
Click the extension icon, then Open Full Scorecard. This opens the full three-tab app: Single Trade, Trade Log & History, and Portfolio Dashboard.
Step 2 — Enter Your Trade Details
Required Fields
Symbol, side (buy/sell), order type (market, marketable limit, or limit), shares, and execution price in USD.
Optional Fields
Commission, fill timestamp (enables time-of-day analysis), broker name (enables cross-broker comparison), and arrival price — a Pro field that unlocks a simplified Implementation Shortfall estimate.
Step 3 — Enter the NBBO at Time of Fill
Enter the NBBO bid and NBBO ask that were live at the moment your order filled. Most broker trade confirmation screens display this, or you can look up a historical quote for that exact second through a market data provider.
Step 4 — Read Your Live Verdict
As soon as all required fields are filled in, your grade badge, price improvement in dollars, effective spread, and E/Q ratio update instantly — no submit button required. A visual diagram plots your fill against the bid, ask, and midpoint so you can see exactly where it landed.
Step 5 — Build Your Trade Log
Click Save Trade to Log to add it to your permanent history. Over time this becomes a personal record you can review, export, or use to compare brokers.
Step 6 — Review Your Portfolio Dashboard
See your total dollar impact across every logged trade, your overall grade, and — with Pro — breakdowns by order type, symbol, broker, and time of day, plus a trend chart showing whether your execution quality is improving or slipping.
Worked Example — Full Calculation Walkthrough
Here's exactly how the numbers move through one real trade.
The trade: Buy 100 shares of a stock at an execution price of $189.42.
The market at that moment: NBBO Bid $189.40, NBBO Ask $189.44.
Midpoint = (189.40 + 189.44) ÷ 2 = $189.42
Quoted Spread = 189.44 − 189.40 = $0.04
Price Improvement (Buy) = NBBO Ask − Execution Price = 189.44 − 189.42 = $0.02 per share, or +$2.00 total on 100 shares
Effective Spread = 2 × |189.42 − 189.42| = $0.00
E/Q Ratio = (0.00 ÷ 0.04) × 100% = 0%
Grade: A — filled exactly at the midpoint, an excellent result.
Try It: Live Execution Grade Calculator
Enter your own numbers to see the same grade the extension would compute.
The formulas behind every number above:
$$\text{Price Improvement (Buy)} = \text{NBBO Ask} - \text{Execution Price}$$
$$\text{Effective Spread} = 2 \times |\text{Execution Price} - \text{Midpoint}|$$
$$\text{E/Q Ratio} = \frac{\text{Effective Spread}}{\text{Quoted Spread}} \times 100\%$$
The Grading Scale
| E/Q Ratio | Grade | Meaning |
|---|---|---|
| ≤ 60% | A | Excellent — significant price improvement |
| 61–85% | B | Good — modest improvement |
| 86–99% | C | Fair — close to NBBO |
| 100% | D | At NBBO, no improvement |
| > 100% | F | Executed outside NBBO — should be rare under Reg NMS Rule 611 |
Where Traders Actually Use This
Active and Day Traders
High-frequency retail traders accumulate dozens of fills a week — a small, consistent execution disadvantage compounds into a meaningful drag on returns that's invisible without a running per-trade record.
Traders Using Marketable Limit Orders
Marketable limit orders are supposed to guarantee a maximum price while still competing for improvement — this tool shows whether that's actually happening or whether fills are consistently landing at the limit price with no improvement at all.
Traders Auditing PFOF-Routed Brokers
For traders using brokers that route orders for payment for order flow, a documented pattern across many trades — not a single anecdote — is what turns a vague suspicion into something worth raising with the broker directly.
A Note on Accuracy
Every calculation is simple, transparent arithmetic — the exact same methodology brokers use in their own Rule 605/606 execution-quality disclosures, applied to your individual trade instead of a firm-wide average. All computation happens locally in your browser. No trade data is ever sent to a server; the only network call this extension makes is an optional license-key check against Gumroad for Pro features.
Common Mistakes (and How to Avoid Them)
Fix: NBBO can shift within the same second in liquid names — use the quote timestamped as close as possible to your actual fill time for an accurate grade.
Fix: One fill can be affected by volatility, order size, or timing beyond anyone's control — look at the trend across many logged trades before drawing a conclusion.
Fix: On a buy, improvement means filling below the ask; on a sell, it means filling above the bid — the formulas are mirrored, not identical, and the extension applies the correct one automatically based on the side you select.
Fix: This tool's shortfall figure is a simplified single-number estimate (execution price vs. arrival price) — a full institutional decomposition into delay, market impact, and opportunity cost requires order-routing timestamps this tool doesn't have access to.
Frequently Asked Questions
Does this connect to my broker automatically?
No. You enter your fill details and the NBBO yourself. This keeps the tool broker-agnostic and avoids the security risk of connecting to a live, authenticated trading session.
Where do I find the NBBO for my trade?
Many broker trade confirmation screens display it directly. Otherwise, a market data provider can supply a historical quote for the specific second of your fill.
What's the difference between price improvement and the E/Q ratio?
Price improvement is a dollar amount — how much better (or worse) your fill was than the NBBO. The E/Q ratio is a percentage showing how your effective spread compares to the quoted spread, which is the same core metric brokers use in their own disclosures.
Is a Grade F proof my broker did something wrong?
No. A single F means that one fill executed outside the NBBO, which should be rare under Reg NMS Rule 611 but can happen for reasons unrelated to broker conduct. Look at your pattern across many trades before drawing conclusions.
What happens to my data after the 14-day trial?
Single-trade calculation, your trade log, and the basic dashboard cards keep working for free indefinitely. Pro features — breakdowns by order type/symbol/broker, the trend chart, and CSV import/export — require a Monthly Pro subscription after the trial ends.
Can I import my existing trade history?
Yes, with Pro — upload a CSV export from any broker and map its columns to the required fields. There's no need for a broker-specific format.
