Who keeps markets honest?

You hand money to an app, which hands it to strangers, to buy invisible property rights from other strangers. That this works billions of times a day rests on an architecture of watchers worth knowing by name.

The three-layer watchtower

• Government regulators. Each major market has one: the SEC in the United States, ESMA coordinating the EU (with national bodies like Germany's BaFin and France's AMF), the FCA in the UK, Japan's FSA. They write the rules: what companies must disclose, what market conduct is illegal, who may sell financial services. Derivatives often have their own regulator (the US CFTC).
• Self-regulatory organizations. The industry polices its plumbing under the regulator's eye — in the US, FINRA oversees brokers (licensing, conduct, the exams from our canon). Exchanges themselves are front-line cops for trading on their venues, running surveillance for manipulation.
• Independent gatekeepers. Auditors certify company accounts; the disclosure machine (quarterly reports, prospectuses, insider-trade filings) exists because rules force information into daylight on a schedule.

Why it exists at all

Every layer answers a historical disaster. The US framework was born from the 1929 crash and its frauds; each generation's scandals (Enron's fake accounts, the 2008 crisis, Madoff) patched new holes. Regulation is scar tissue — markets learned honesty the expensive way.

What it does and doesn't promise

Watchers pursue fair play: truthful disclosure, honest trading, segregated client assets (Course 1). They do NOT promise you won't lose money on a fair bet gone wrong — a losing investment isn't a crime, and no regulator refunds it. The promise is a clean game, not a winning hand.

In the data

That daylight is a public document. Every insider trade in a US-listed company is reported on a Form 4, filed with the SEC, and each one says who traded and in what role, whether they bought or sold, how many shares at what price, and two dates that are not the same: the day of the trade and the day the filing appeared. Here is the latest one for Apple:

The footnote is often the most important row: it is where you learn that a sale was pre-scheduled under a Rule 10b5-1 plan rather than decided that morning. And the gap between the two dates is precisely how long the public did not know. The rule covers companies listed in the United States; other countries run their own disclosure regimes.

Try it now

1. Find who regulates the exchange your anchor company lists on.
2. Open a filings feed — the disclosure machine at work: every document there exists because a rule demands it. Apple's is linked below; for your own anchor company, change the symbol there.

Open AAPL.US — filings in the EODHD Terminal

3. Now measure the daylight. Apple's five most recent insider filings are below: for each, the day the insider traded and the day the public found out. Subtract one from the other on each and write down the largest gap you find.

Days, not months: the rule allows two business days, so anything much beyond that is either a weekend, a holiday, or something worth a second look. 4. Read the footnotes on the widest one before you conclude anything. Every Form 4 is public on the SEC's EDGAR site: search for Apple Inc., filter the filings to type 4, and open the one filed on the date in your table; the footnotes sit at the foot of the form. A sale filed under a Rule 10b5-1 plan was scheduled months earlier by someone who could not have known what they know today, and that is a different story from a sale decided the morning it happened.