---
title: "Hours, Rhythm and Intensity"
book: "The Industry: Firms, Roles and Careers"
subject: quant
language: en
chapter: 26
exercises: 8
source: https://one-course.com/books/quant/17/en/chapter/26-hours-rhythm-and-intensity
---

# Chapter 26 — Hours, Rhythm and Intensity

Laid on one clock, UTC, four of the world’s large futures markets leave 48 hours of an ordinary week with none of them open: from Friday evening in New York to Sunday evening in New York. Since 29 May 2026 the largest US futures exchange has traded crypto futures around the clock, closing only for two two-hour maintenance windows a week; a book that adds them leaves two hours of the week unwatched. A desk’s hours are set by the markets it trades before any firm decides anything, and on-call is the price of markets that never close. This chapter measures the hours a desk must cover, turns them into shifts and headcount under the working-time rules, and separates what is documented about hours in the industry from what is anecdote.

## 26.1 Market hours by product, in one time zone

**Definition 26.1 (Coverage requirement).**

A desk’s *coverage requirement* is the set of hours in a week, on one clock, during which at least one market the desk trades is open and so someone must be able to act: watch positions and systems, answer alerts, and stop trading if needed.

Exchanges publish their sessions in local time, and their cities change clocks for summer on different dates, or, like Hong Kong, not at all; firm.calendar (Book 1, chapter 22) converts them to UTC through the time-zone database, and Book 3, chapter 29, draws the map of all markets on one clock. The chapter’s five markets are US Treasury note futures, Brent crude oil futures, EURO STOXX 50 futures, Hang Seng index futures and bitcoin futures.

**As of September 2026 — Sessions of the chapter’s five markets.**

CME 10-year Treasury note futures: “CME Globex: Sunday - Friday 6:00 p.m. - 5:00 p.m. ET”. ICE Brent crude futures: 01:00–23:00 London, Sunday open 23:00. Eurex EURO STOXX 50 futures: 02:10–22:00 CET. HKEX Hang Seng index futures: 09:15–12:00, 13:00–16:30 and 17:00–03:00 Hong Kong time. CME cryptocurrency futures: 24/7 trading “went live on Friday, May 29” 2026, with Globex maintenance windows on Saturday and Tuesday from 2:00 to 4:00 a.m. Central Time.

![Number of the chapter’s five markets open in each hour of the week of 21–27 September 2026, in UTC (hourly averages). The weekday rows are covered around the clock by futures; from Friday 22:00 to Sunday 22:00 only crypto futures trade, and they pause on Saturday from 07:00 to 09:00 UTC. Data: in_hours.heat, from firm.workload.week_matrix on data/industry/sessions_desk.csv.](https://one-course.com/images/onecourse/chapters/quant-17/in-hours-rhythm-and-intensity/fig-02d11c4e780f.svg)

***Figure 26.1.** Number of the chapter’s five markets open in each hour of the week of 21–27 September 2026, in UTC (hourly averages). The weekday rows are covered around the clock by futures; from Friday 22:00 to Sunday 22:00 only crypto futures trade, and they pause on Saturday from 07:00 to 09:00 UTC. Data: `in_hours.heat`, from `firm.workload.week_matrix` on `data/industry/sessions_desk.csv`.*

The week of [Figure 26.1](#fig-in-hours-rhythm-and-intensity-heat) has 168 hours. The four non-crypto futures are open, one or another, for 120 of them: Monday 00:00 to Friday 22:00 UTC, with no gap during the week because each market’s daily break falls inside another’s session. The Treasury note futures trade 115 hours, Brent 112, the EURO STOXX 50 futures 99.2 and the Hang Seng futures 81.25. Adding the crypto futures leaves 166 hours covered and one gap, the Saturday maintenance window.

## 26.2 On-call and markets that never close

A desk that trades only weekday futures can staff the week and rest at weekends; its systems still need someone who can be reached if they fail between sessions. A desk that adds a market that never closes must staff, or at least watch, every hour. Book 15, chapter 28, describes the tools (on-call rotations, runbooks, an incident commander); this chapter counts the people.

**Method 26.2 (Shifts and headcount).**

Cover each day’s open minutes with the fewest shifts of length $L$ hours overlapping by $o$ hours (firm.marketmap’s planner); round-the-clock cover needs $\lceil 24/(L-o)\rceil$ shifts a day. With $H$ shift-hours a week, $k$ people on each shift, an average working week of at most $W$ hours and $\ell$ weeks of leave a year, the headcount is at least

$$
N=\frac{H\,k}{W\,(52-\ell)/52}.
$$

On-call load is the nights to cover a month divided by the rota’s size.

**Example 26.3 (A futures book and a futures-and-crypto book).**

With nine-hour shifts overlapping by one hour, two people a shift, a 48-hour average week and four weeks of leave: the four futures need three shifts on each weekday and one on Sunday evening, 144 shift-hours a week and $6.5$, so 7, people. Adding the crypto futures needs three shifts every day, 189 shift-hours and $8.53$, so 9, people; without leave the bound would be 7.9. An on-call rota of eight engineers covering every night of the month gives each 3.8 nights a month.

| book | open hours a week | shift-hours a week | people (bound) | people |
| --- | --- | --- | --- | --- |
| futures only | 120 | 144 | 6.5 | 7 |
| futures and crypto | 166 | 189 | 8.53 | 9 |

## 26.3 Working-time rules

**Definition 26.4 (Working-time opt-out, exempt employee).**

A *working-time opt-out* is a worker’s written agreement, allowed by EU law where a Member State chooses and by UK law, to work more than an average of 48 hours a week; it can be withdrawn on notice. An *exempt employee*, in US law, is one whom the Fair Labor Standards Act’s overtime rules do not cover because of the job’s duties and a minimum salary.

**As of September 2026 — Working-time rules.**

European Union, Directive 2003/88/EC: average working time, “including overtime”, not above 48 hours for each seven days (art. 6); at least four weeks of paid annual leave (art. 7); a Member State may allow longer hours with the worker’s prior agreement, no detriment for refusing and records kept (art. 22). United Kingdom, Working Time Regulations 1998: the 48-hour average applies “Unless his employer has first obtained the worker’s agreement in writing” (reg. 4); the worker can end the agreement on notice of seven days to three months (reg. 5). United States: the Department of Labor enforces the 2019 salary level for [exempt employees](#def-in-hours-rhythm-and-intensity-rules), $684 a week ($107 432 a year for highly compensated employees), after a federal court vacated the 2024 rule on 15 November 2024.

The rules bind differently. In the European Union the 48-hour average is the default, and the opt-out is individual and revocable; the chapter’s headcount uses it as the limit. In the United States most quantitative staff are paid far above the salary level and are exempt, so the law sets no limit on their hours; the limit is the firm’s. In both, the desk’s [coverage requirement](#def-in-hours-rhythm-and-intensity-coverage) does not move: the law decides how many people it takes, not how many hours need covering.

## 26.4 What is documented and what is anecdote

Hours are among the most discussed and least measured features of the industry. The inputs to this chapter’s model carry a status, and the chapter uses only three kinds.

- **Documented** : the exchanges’ sessions and the working-time rules, from the exchanges and the legal texts.
- **Press** : a bank’s policy reported by a reputable publication with the bank’s confirmation. JPMorgan, for example, “will limit junior banker hours to 80 per week in most cases, as confirmed by the company to Fortune” (2024); that is a statement about junior investment bankers, not about trading or quantitative staff.
- **Illustrative** : the shift length, overlap, people per shift and rota, which are the modeller’s choices.

The fourth kind, anecdote (posts, forums, interview stories of eighty-hour weeks or of leaving at five), is not data: it is selected by who speaks and when, and this chapter uses none of it. What can be said with evidence is structural: which hours a desk must cover, how many people that takes under the law, and which roles carry on-call (chapter 20) rather than how long any person works.

## 26.5 Tutorial: who watches Sunday night?

**Goal.** Compute a desk’s [coverage requirement](#def-in-hours-rhythm-and-intensity-coverage) from its markets, and the shifts, headcount and on-call load it implies. **End state:** Figures [26.1](#fig-in-hours-rhythm-and-intensity-heat) and [26.2](#fig-in-hours-rhythm-and-intensity-shifts) and the staffing table.

1. **Sessions.** `data/industry/sessions_desk.csv` , loaded with Book 1’s `firm.calendar` , each row sourced.
2. **The week in UTC.** `firm.workload.week_matrix` marks each market’s open minutes on one UTC week ([Listing 26.1](#lst-in-hours-rhythm-and-intensity-week)); `open_hours` and `closed_spans` summarise it. `def week_matrix (sessions, roots, monday: dt.date): """Open (True) or closed for each root and each UTC minute of the week that starts at monday 00:00 UTC.""" start = dt.datetime.combine(monday, dt.time(0 ), cal.UTC) m = np.zeros((len (roots), WEEK), bool ) for i, root in enumerate (roots): for d in range (7 ): for a, b in cal.utc_intervals(sessions, root, monday + dt.timedelta(days=d)): lo = int ((a - start).total_seconds() // 60 ) hi = int (math.ceil((b - start).total_seconds() / 60 )) m[i, max (lo, 0 ):min (hi, WEEK)] = True return m` **Listing 26.1.** Each market’s open minutes on one UTC week. code/firm/workload/firm_workload.py
3. **Shifts.** `to_markets` and `shift_table` hand the week to Book 3’s `firm.marketmap` planner.
4. **People.** `headcount` and `oncall_nights` ([Listing 26.2](#lst-in-hours-rhythm-and-intensity-people)). `def continuous_shifts (length_h, overlap_h): return math.ceil(24.0 / (length_h - overlap_h)) def headcount (staffed_hours_week, per_shift, max_week_h=48.0 , leave_weeks=4.0 , weeks=52.0 ): """People needed so that staffed_hours_week x per_shift person-hours fit under an average of max_week_h hours a week, with leave_weeks of leave a year (the EU minimum is four).""" return staffed_hours_week * per_shift / (max_week_h * (weeks - leave_weeks) / weeks) def oncall_nights (nights_per_month, rota): return nights_per_month / rota` **Listing 26.2.** Shifts for round-the-clock cover, headcount under a working-time limit, and on-call nights. code/firm/workload/firm_workload.py

![Lower bounds on the people needed for two books, with two people on each nine-hour shift and a 48-hour average week, with and without four weeks of leave. Round up for the headcount. Data: in_hours.staffing, from firm.workload.headcount.](https://one-course.com/images/onecourse/chapters/quant-17/in-hours-rhythm-and-intensity/fig-b56aa26cbe74.svg)

***Figure 26.2.** Lower bounds on the people needed for two books, with two people on each nine-hour shift and a 48-hour average week, with and without four weeks of leave. Round up for the headcount. Data: `in_hours.staffing`, from `firm.workload.headcount`.*

The results: 120 open hours for the futures, 166 with crypto; 7 and 9 people; 3.8 on-call nights a month for each of eight engineers.

**What to change next.** Load the exchanges’ holiday calendars; let people per shift follow the number of markets open; add the ramp before an open and the reconciliation after a close; model on-call calls as a Poisson process (chapter 16) rather than as nights.

## 26.6 Build: firm.workload

**Purpose.** Turn a desk’s markets into its [coverage requirement](#def-in-hours-rhythm-and-intensity-coverage), shifts, headcount and on-call load, with the status of every input.

**Interface.** `firm.workload`: `Input(name, value, unit, status, source)`, `by_status`; `week_matrix(sessions, roots, monday)`; `open_hours`; `closed_spans`; `to_markets`; `shift_table(markets, length_h, overlap_h)`; `continuous_shifts`; `headcount(hours, per_shift, max_week_h, leave_weeks)`; `oncall_nights(nights, rota)`; on `firm.calendar` and `firm.marketmap`.

**Rules.** Sessions in local time, converted through the time-zone database; one UTC week; an input’s status is one of documented, press, anecdote, illustrative, and anything else is an error.

**Acceptance tests.** `code/firm/workload/tests/`: a London session appears an hour earlier in UTC in summer; a round-the-clock market leaves no gap; 96 hours with four weeks of leave need $2\times52/48$ people; two overlapping markets get the planner’s shifts.

**Stretch.** Holidays; skills per shift (not everyone can watch every market); fatigue rules between shifts.

Sources and further reading

- CME Group, ICE, Eurex and HKEX product pages; CME Group, 24/7 crypto futures (June 2026).
- Directive 2003/88/EC; Working Time Regulations 1998; US Department of Labor, overtime rulemaking.
- Fortune (2024), JPMorgan’s junior banker hours.
- Book 1, chapter 22; Book 3, chapter 29; Book 15, chapter 28.

## 26.7 Exercises

**Exercise 26.1 ★.**

How many hours of the week are the four non-crypto futures all closed, and when?

**Solution of Exercise 26.1.**

48 hours: from Friday 22:00 UTC, when Brent closes (23:00 London), to Sunday 22:00 UTC, when the Treasury note futures (18:00 New York) and Brent (23:00 London) reopen, in the chapter’s September week.

**Exercise 26.2 ★.**

How many eight-hour shifts overlapping by 30 minutes cover a day round the clock?

**Solution of Exercise 26.2.**

$\lceil 24/7.5\rceil=4$ shifts.

**Exercise 26.3 ★.**

With the example’s rota, how many on-call nights a month does each engineer carry if the rota grows to twelve?

**Solution of Exercise 26.3.**

$30.44/12=2.5$ nights a month.

**Exercise 26.4 ★★.**

Why does the Treasury note futures’ daily one-hour break not create a gap in the four-market week?

**Solution of Exercise 26.4.**

Its break, 17:00 to 18:00 New York time (21:00 to 22:00 UTC in summer), falls inside Brent’s session, which runs until 22:00 UTC; and Brent’s own break, 22:00 to 00:00 UTC, falls inside the Treasury session.

**Exercise 26.5 ★★.**

Recompute the futures-and-crypto headcount with three people on each shift.

**Solution of Exercise 26.5.**

$189\times3/(48\times48/52)=12.8$, so 13 people.

**Exercise 26.6 ★★.**

A London desk’s traders have all signed the [working-time opt-out](#def-in-hours-rhythm-and-intensity-rules). What does that change in the headcount, and what does it not?

**Solution of Exercise 26.6.**

The 48-hour average no longer binds, so fewer people could cover the same shifts on paper; but each can withdraw on notice, leave and fatigue remain, and the [coverage requirement](#def-in-hours-rhythm-and-intensity-coverage) and the need for two people on a shift do not change. A plan that relies on opt-outs is fragile.

**Exercise 26.7 ★★★.**

*Coding.* Run the week of 23–29 March 2026, when the United States has moved to summer time but Europe has not. How do the open hours and the closed span change?

**Solution of Exercise 26.7.**

The futures are open 121 hours instead of 120, and the closed span is 47 hours, from Friday 23:00 to Sunday 22:00 UTC: Brent closes at 23:00 London time, which is still 23:00 UTC before Europe’s clocks change on 29 March. The crypto week is unchanged, 166 hours.

**Exercise 26.8 ★★★.**

*Find the flaw.* “Quants at trading firms work eighty-hour weeks: a friend at one told me, and a forum thread agrees.”

**Solution of Exercise 26.8.**

Two anecdotes selected by who chose to speak are not a measure; they do not say which firm, role, season or year, and cannot be checked. The documented facts are the markets’ hours, the legal limits and the published policies; hours actually worked are not measured by any public source this book found.

## 26.8 Problem: Who Watches Sunday Night?

**Problem 26.1.**

Weekend problem — who watches Sunday night?

A firm that trades the four futures plans to add CME’s crypto futures, and its head of trading asks how many people the desk will need.

**Part I — The hours.**

1. Define the [coverage requirement](#def-in-hours-rhythm-and-intensity-coverage) .
2. State the five markets’ sessions and their sources.
3. Why must sessions be converted through the time-zone database?
4. Give the open hours a week of each market and of the four futures together.
5. When is nothing open once crypto is added?

**Part II — The staffing.**

6. State the headcount formula.
7. How many shifts does round-the-clock cover need with nine-hour shifts and a one-hour overlap?
8. Compute the shift-hours a week for each book.
9. Compute the headcount bounds with and without leave.
10. Compute the on-call nights a month for a rota of eight.

**Part III — The rules and the evidence.**

11. State the EU working-time limit and the leave minimum.
12. What is the UK opt-out and how is it ended?
13. Who is an [exempt employee](#def-in-hours-rhythm-and-intensity-rules) in the United States, and what salary level does the Department of Labor apply?
14. Which of the model’s inputs are documented, which illustrative?
15. Why is no anecdote used?

**Part IV — The verdict.**

16. State the *named result* : the smallest headcount that covers the futures-and-crypto book around the clock under a 48-hour average week with two people on each shift, and the on-call nights per engineer a month for a rota of eight.
17. How many people does adding crypto cost?
18. What else, beyond people, does round-the-clock trading need?
19. What would opt-outs change?
20. In two sentences, answer the head of trading.

**Solution of Problem 26.1.**

1. As in the chapter’s definition.
2. As in the sessions box, from the CME, ICE, Eurex and HKEX pages and CME’s announcement.
3. Because each exchange publishes local times and the cities change clocks on different dates or not at all.
4. Treasury notes 115, Brent 112, EURO STOXX 50 99.2, Hang Seng 81.25; the four together 120 of 168.
5. Saturday 07:00 to 09:00 UTC, the crypto futures’ maintenance window.
6. $N=Hk/(W(52-\ell)/52)$ .
7. Three.
8. 144 for the futures, 189 for futures and crypto.
9. 6.5 and 8.53 with four weeks of leave (7 and 9 people); 6.0 and 7.9 without.
10. 3.8.
11. 48 hours on average including overtime; four weeks of paid leave.
12. A written agreement to work longer, ended by the worker on seven days’ notice or a longer agreed period up to three months.
13. A salaried employee whose duties exempt them from overtime, above $684 a week under the enforced 2019 rule.
14. Documented: sessions, limits, leave; illustrative: shift length, overlap, people per shift, rota.
15. It is unmeasured and selected; it cannot be checked.
16. 9 people; 3.8 on-call nights a month per engineer.
17. Two people.
18. Automated monitoring and kill switches, weekend support from the exchanges, the clearing member and the firm’s own operations, and a plan for the maintenance windows.
19. On paper fewer people; in practice nothing reliable, since opt-outs can be withdrawn.
20. Nine people on two-person shifts cover the combined book under the European limit, two more than the futures alone. Budget for the weekend support around them too.

## 26.9 Interview questions

**Interview question 26.1 ★ trader.**

You are alone on the desk at 3 a.m. and a strategy starts losing quickly. What do you do?

**Solution of Interview question 26.1.**

Stop the strategy (kill switch or disable), confirm the position and exposure, reduce risk if needed within your authority, and call the escalation contacts; investigate after, and document.

*What the interviewer is looking for: act first within authority, then escalate.*

**Interview question 26.2 ★ developer.**

What belongs in a runbook for a market-data outage?

**Solution of Interview question 26.2.**

How to detect it, which strategies to stop, the fallback feeds, whom to call at the exchange and internally, how to recover and verify, and how to record the incident.

*What the interviewer is looking for: detection, containment, contacts and recovery.*

**Interview question 26.3 ★★ developer.**

How would you convert an exchange’s session times to UTC for the next year, and what goes wrong?

**Solution of Interview question 26.3.**

Store sessions in local time with the time-zone name, generate UTC intervals from the time-zone database for each date, and load exchange holiday calendars; what goes wrong is the weeks when some zones have changed clocks and others have not, and holiday half-days.

*What the interviewer is looking for: local time plus a time-zone database, never fixed offsets.*

**Interview question 26.4 ★★ trader, risk.**

How would you hand over a book between shifts in London and Singapore?

**Solution of Interview question 26.4.**

A written handover of positions, limits, open issues and planned events; an overlap long enough to talk; a check that the receiving desk sees the same positions and risk; and one owner at every moment.

*What the interviewer is looking for: overlap, written state and single ownership.*

**Interview question 26.5 ★★ developer.**

How would you reduce the number of times the on-call engineer is woken without missing real incidents?

**Solution of Interview question 26.5.**

Page only on symptoms that need a human now, route the rest to tickets, remove duplicate alerts, add runbooks and automated fixes for common causes, and review every page after the fact.

*What the interviewer is looking for: actionable alerts only.*

**Interview question 26.6 ★★★ developer, trader.**

Design the staffing and automation for a desk that trades crypto around the clock with only five people.

**Solution of Interview question 26.6.**

Automate the watching (risk limits, kill switches, health checks that stop trading on failure), run smaller risk outside staffed hours, keep one person on call with a second as backup, and review the incidents weekly; accept that without people the risk taken at night must be small.

*What the interviewer is looking for: automation and lower risk outside staffed hours.*