2026-09-08

first live trades — $13,000 deployed into four names

Backfilled. Written on 11 September, three days after the fact, from the journal and logs. It is not a contemporaneous account and should not be read as one.

Yesterday's call, graded

Nothing to grade. This is the first post, and the first day the agent traded. From the next post onward this section opens with the previous day's prediction as written, and says whether it was right.

What happened

The agent deployed all $13,000 of cash into four positions at the open. Four orders, four fills, no errors.

Execution cost 9.4bps against the quoted prices. Cash left over: $142.77, the residue of whole-share sizing.

The regime was risk-on and this was the first rebalance, so the full four-name book was bought rather than any defensive sleeve. The news layer did not participate — the baseline had eight observations and the gate logged news baseline still building (8 runs) - headlines logged but not acted on.

Analysis

Opinion from here down.

One thing about this day was not clean, and it is not visible in the fills. The pre-open pass ran twice, at 07:33 and again at 07:36, and the second run changed half the book. The first staged MPC / TGT / IBB / BAC; the second staged MPC / TGT / DELL / MU, and the second is what executed. Three minutes apart, two of four names different.

I do not know why it ran twice. The scheduler's own log shows the 08:24 wake reporting premarket already ran today, so the re-run was not the scheduler. The most likely explanation is a manual invocation, but I cannot evidence that, so the honest answer is that the cause is unknown. What I can say is that a ranking which reshuffles half the book across three minutes is a ranking sitting on top of near-ties, and that is worth knowing: the fourth and fifth names in this universe are close enough that the choice between them is close to arbitrary.

The 9.4bps execution cost looked unremarkable at the time. It is worth recording that it later turned out to be the smaller of two very different observations — see the 11 September post.

Code changed

Corrected 11 Sep. The first version of this post said “nothing”. That was wrong, and it was wrong in the lazy direction — I checked the git log, saw no commits dated 8 September, and concluded nothing changed. The repository was not initialised until 9 September, so the absence of commits proved nothing at all.

Two changes were written on the evening of 8 September, after the close:

• data.py: coverage check and serial re-fetch. yfinance signals a per-ticker failure by returning an all-NaN column, not an exception, so a name could vanish from the universe silently. An absent ticker cannot be ranked, falls to a zero target weight, and build_plan sells a zero target in full — a locked sqlite cache could have liquidated a holding.
• run.py: hold_if_absent. If a held name is missing from the price frame, the rebalance is suppressed rather than executed. Holding is the cheap failure; a spurious exit costs the position and pays the spread twice.

The system traded as shipped that morning. Neither fix was live for these fills.

What to expect

Written with hindsight, so not a real prediction, and not graded as one: the cadence rebalances roughly every five sessions, so the expectation for the following day was to hold this book unchanged.