The original strategy enters when a trend first appears. Repeated reversals may create costs. Would waiting for another month-end confirmation help? A small rule change sounds promising, but the second confirmation can also make you buy later at a higher price.
Investigate only this change. The task is not to adjust it until profitable. Deliver a conclusion someone else can check: what the rule actually does, what the results support, and which work remains incomplete.
Record two kinds of completion separately
You will freeze one limited variant, compare inputs and predictions with a complete ledger, and deliver a T05/T06 package preserving negative results and blocked scope. A supplied mechanism exercise can be complete while independent real research remains blocked by data or tool limitations.
The real time-series route retains SPY and cash, warmup from 2006, and the 2007–2024 teaching interval. Original C2-A is long-only and unleveraged. After month-end close, it holds only when the total-return index is strictly above the average of ten valid month-end values, including the current month. Otherwise, including equality, target cash. Process the target at the next normal trading open, not the signal-generating close. Costs, corporate actions, capital, and pending-target policies remain fixed.
The $10,000 is teaching capital in a separate strategy subaccount, not an amount every household should invest. G72/G73 identify money that cannot bear this uncertainty. Passing a research check supplies no additional household percentage or transfer authority.
Specify how B can fail before looking for success
Register C2-B-confirm2-v1. Only first entry and reentry require two consecutive, adjacent, valid month-ends, each strictly above its own ten-valid-month average. Exit retains the original rule: one equal or below-average observation targets cash. If already invested and currently above, maintain the position rather than buying a second holding because another confirmation occurred.
An invalid current observation or insufficient history creates no new target and breaks the confirmation sequence. Preserve actual cash and shares. At each new month-end, expire the previous unfilled simulated target before checking the new input. Invalid information is not a sell signal; expiration of a simulated target is not proof that a broker canceled an order.
The proposed mechanism is fewer unstable entries. Competing explanations include delayed exposure, missed gains, or confirmation near a high. Compare only this B. Log any other window or threshold tried. No profit, no drawdown improvement, or an advantage erased by costs is an acceptable finding. Do not replace a losing variant before handing in the assignment.
Define comparisons and assumptions first: A, B, and same-capital buy-and-hold; base commission 5 basis points plus directional price slippage of 5 basis points; 0/0 and 15/15 scenarios; and a separate delay of one additional normal trading day. These are teaching assumptions, not brokerage quotes. Better performance on one metric does not automatically establish alpha or future usefulness.
Begin real acquisition with identity and fields
The issuer's SPY page identifies ticker SPY, trading currency USD, ISIN US78462F1030, and NYSE ARCA. It also explains its market Closing Price field.[1] Reading that page establishes an asset and field entry point, not possession of a historical dataset.
NAV differs from market price. Research needs original regular-session opens and closes, cash distributions, splits, and a calendar, plus an explanation of the total-return signal's construction. Today's one closing quote cannot replace years of history. A total-return index cannot simultaneously serve as an executable share price with distributions added again.
Save source, acquisition date, identity, units, time zone, revisions, missing-data rules, and permissions. Public readability does not establish redistribution rights. The complete lawful 2007–2024 package has not been obtained; the recorded acquisition attempt also did not complete access through the historical-distributions link. Do not describe the real backtest as finished. This chapter's current identity check does not fill that historical gap.
Complete a small mechanism instead of only making a checklist
The C2-B synthetic package provides fixed specifications, month-end and trading-day inputs, prediction checkpoints, A/B/benchmark ledgers, four cost-and-execution scenarios, failure records, and conclusion limits. Its explanatory notes are currently in Chinese; CSV fields and the following walkthrough make the mechanism checkable. Every value is synthetic and already known to the authors, not SPY history.
M01–M09 month-end index values are all 100. M10–M16 are 110, 120, 90, 100, 120, 130, and 100. Each active teaching month supplies FIRST and LAST normal trading days with separate raw opens and closes. There are no distributions or splits, so the total-return index happens to equal the close. Execution still reads the independent open column.
These are symbolic months, not actual New York dates. The package uses an America/New_York teaching clock, 09:30 open and 16:00 close, without inventing UTC or daylight-saving conversions. Signals follow LAST close. Base execution first becomes possible at the next month's FIRST open; an additional-day delay reaches the next supplied normal day.
Before opening answers, predict M10's mean, whether B buys immediately, its earliest possible entry, and its response when M12 falls below the average. If answers were already viewed, label the exercise retrospective checking, not an independent blind test.
M10's ten observations sum to 1,010, averaging 101. The current 110 exceeds it, but this is only B's first confirmation, so B still targets cash. M11's mean is 103; 120 supplies the second confirmation. The earliest purchase is M12-FIRST open. A enters after the first confirmation, so both timing and purchase price can differ.
Reconcile a purchase before trusting an endpoint
Under base costs, M12-FIRST's raw open is 120. B's buying price is 120 × 1.0005 = 120.06. The fee-inclusive upper quantity is $10,000 divided by 120.06 and then by 1.0005. Round down to one-millionth of a share: 83.250062 shares.
Total expenditure is $9,999.99994494186, leaving $0.00005505814. Do not erase the remainder for neatness or permit negative cash. At M12's $90 closing valuation, equity is $7,492.50563505814. The index is no longer above its mean of 102, creating a cash target.
At M13-FIRST, the raw $90 open becomes a selling price of 89.955 after directional slippage. Selling commission is $3.744379663605; cash after exit is $7,485.015002604535. Keep price, commission, shares, and cash separately. The same commission cannot be deducted again from an already-net value.
The model uses 28-digit decimal arithmetic, without rounding each cash movement to cents. Fractional precision is a teaching implementation policy, not a claim about every broker. M14 supplies the first new above-average confirmation, M15 the second; B buys again at the supplied M16-FIRST $130 open, then exits at M17-FIRST after M16 closes below average. The full signal and daily ledgers preserve the intermediate states.
Hand over the negative result too
| Base 5/5 basis points; initial $10,000 each | Ending equity | Cumulative return | Maximum observed drawdown |
|---|---|---|---|
| Original A | 6790.963585 | −32.090364% | 37.687234% |
| Confirmation B | 5746.199965 | −42.538000% | 42.538000% |
| Buy-and-hold | 9990.007495 | −0.099925% | Approximately 25% |
The endpoint is M17-LAST close. Do not add a forced-sale fee to the still-held benchmark; the strategies have already exited under their rules. Drawdown includes initial equity and supplied observation points. Sparse synthetic days do not establish actual intraday maximum drawdown. The symbolic interval supplies neither annualization nor a credible alpha or Sharpe estimate.
B improves neither return nor observed drawdown here. Its confirmation mechanism can still be implemented consistently. The artificial path cannot establish that real B must fail. Accept the mechanism check while rejecting an unsupported investment advantage.
B makes money under the additional-delay scenario; retain that result as well. The synthetic open path happens to favor delayed transactions. This does not retroactively register delay as a new winning strategy. Delay also affects the benchmark's first entry, and an additional normal day at M17 allows the pending delayed exit to finish under matching cutoff conditions.
Preserve the failure, recovery, and unsupported input states
The package records an actual author-side missing-input test: a nonexistent month-end input path caused failure and produced no new result. Restoring the default path allowed the original checks to pass. Old expected files still present during failure were not newly produced output.
Four boundary exercises also matter: nine observations generate no target; missing M11's current index leaves A's existing shares while B stays in cash; ten equal values of 100 target cash; and missing M12 open prevents a fill until the next supplied valid open. Preserve reasons instead of inventing prices or writing expected values back as actual results.
The fixed package distinguishes an empty signal field from a deleted month. Month rows must be unique, ordered, and continuous: deleting M11 cannot make M10 and M12 adjacent confirmations. It supports only the stated normal-session and no-corporate-action inputs. Unsupported action markers fail at entry rather than silently inherit the old result. Real distribution, split, and calendar handling remains a separate implementation task.
Author scripts provide another numerical checking route, not a requirement to install Python. A spreadsheet can expose the CSV arithmetic, but your chosen tool must actually import rules and data, show a complete ledger, and export it. An author temporarily rewriting source code and running the task for you does not establish independent completion.
Identify what independent research still requires
T05 freezes rules and the data contract; T06 states conclusions and affected scope. Include lawful materials or acquisition instructions, tool and setting versions, signals and orders, fees, cash, holdings, benchmark, all attempts, and rerun instructions. Another person should find your actual outputs, not only the authors' expected answers.
Retain real-history partitions: 2007–2014 development, 2015–2019 validation, 2020–2024 historical teaching holdout. Material known or used for changes cannot be renamed unknown. Synthetic M10–M16 roles do not replace those long intervals. Actual forward observations begin after freezing; T09 currently says planned observations; not started.
Without complete lawful real data and a verified tool path requiring no source edits, real independent research R4 remains blocked. Record the supplied mechanism exercise separately as complete. The factor route additionally needs G87, stock-level C9 materials, and T17; a time-series result does not demonstrate factor competence. Changed-household RISK and exception-recovery RUN each require their own evidence.
Change one input before choosing the conclusion
Explain why profitable delayed B cannot overturn the base loss. Then change only M11's month-end index to missing. Immediately after that decision, what do A and B actually hold, and does B's confirmation sequence continue?
The delay result uses another execution assumption on already-seen synthetic inputs. Report both scenarios with registered versions and attempt limits; selecting the winner is not independent validation.
A bought at M11-FIRST under M10's earlier target. Invalid new information is not liquidation, so it retains actual shares. B has not entered and remains in cash; its first confirmation is interrupted. Expired old simulated targets cannot support a later catch-up purchase. Later M12 information cannot be backfilled into M11 as if known then. One missing field can leave the two accounts with different actual risks.
Deliver a package with a defensible scope
Save registration, identity and permission records, first predictions, actual tool outputs, discrepancy locations, all four scenarios, failure and recovery logs, and T06's conclusions and gaps. Separate expected answers from your output. List missing materials and their effect; “prepared to download” is not “obtained.”
Check one changed rule, signal-before-fill ordering, reconciled cash and fees, retained losses, and author-versus-reader work. Ask a successor to trace M11's signal to M12's purchase and then M13's exit cash. If only expected answers can be found, tool reproduction remains unverified. If everything reconciles, update only the corresponding mechanism status.
Allow the variant to fail, then limit conclusions to the available data and implementation evidence. Stopping accurately at a lawful-data or tool gap is a more useful research result than manufacturing a complete-looking curve. Rule implementation, research evidence, and investment advantage remain separate decisions.
References
- State Street Investment Management, official SPY fund page. Listing Information, trading currency, identity, and Closing Price definition only—not the synthetic inputs, complete historical package, or redistribution permission.
Source checked October 30, 2026. AI-assisted draft; independent AI full-text and bilingual review is complete. Human financial review and target-reader testing have not been conducted and are not scheduled for this production round. Synthetic mechanism checks do not complete real R4, T09, RISK, or RUN.