1
Trading calendar
Open, close, holiday, half-day, and instrument-session rules.
Lesson · Algorithmic and Automated Trading
Time, Sessions, Events, and Scheduling
Use exchange calendars, time zones, session boundaries, event windows, and deterministic schedulers instead of assuming every day and minute is tradable.
Core concepts
What to understand
Keep the boundaries, state, and authority explicit.
2
Event window
A defined period around earnings, news, auctions, or scheduled releases.
3
Scheduler state
Record planned run, actual run, skipped run, lateness, and recovery action.
Interactive lab
Market Clock and Scheduler Lab
Change session rules, clock drift, scan frequency, and event blackouts. Observe late, skipped, and valid executions.
Market Clock and Scheduler Lab
Deterministic synthetic educational data · no broker or live-market connection
SYSTEM MODEL
Process
Use one authoritative clock
Every event and decision should use explicit timezone and session metadata.
Resolve
Load the correct calendar and current session state.
Schedule
Create deterministic jobs with deadlines and idempotent run identifiers — an identifier the scheduler can be handed twice without running the job twice; Reliability, Idempotency, Retries, and Recovery makes the idea precise.
Guard
Skip or require approval when the job is late or inside a blocked event window.
Knowledge check
Check your understanding
Select one answer for each question. Feedback appears immediately, and a wrong choice is answered on its own terms before the rule is restated.
1. Why is a weekday check insufficient?
Trading calendars include closures, half-days, and instrument-specific sessions.
2. A late signal should be:
The market may have moved beyond the conditions that produced it.
3. A deterministic scheduled run should have:
A stable identifier supports deduplication and recovery.
4. The exchange opens at 09:30 New York. A server on UTC schedules the open job at 13:30 UTC all year. In November, when does the job run in New York time?
13:30 UTC is 09:30 EDT in summer and 08:30 EST in winter. The calendar carries the offset; a scheduler that hard-codes it is right for half the year.
Practical rules
- Use exchange calendars rather than fixed weekday logic.
- Define maximum signal and job age.
- Use explicit event blackouts and session permissions.
Common mistakes
- Assuming local server time equals exchange time.
- Running missed jobs later without revalidation.
- Ignoring early closes and daylight-saving changes.
References
Official reading
These sources cover algorithmic controls, market access, broker APIs, system operations, or security.
Alpaca · WebSocket Market Data
Official example of receiving real-time stock, option, crypto, and news updates over a streaming API.
FINRA · Regulatory Notice 15-09
Official guidance on supervision, testing, controls, documentation, and monitoring for algorithmic trading strategies.