Insider signals in the stock market: using regulatory filings
When a CEO buys their own shares in size, it is rarely an accident. Insider transactions disclosed to the market regulator are a legal and under-used source of information, particularly useful on Euronext Growth small caps with thin analyst coverage.
May 2026
8 min read
Intermediate level
What is an insider signal?
Persons connected to an issuer (directors, board members, controlling shareholders) are required to disclose to the national market regulator any transaction in the company's securities within 3 business days of the operation. This is a regulatory obligation under the EU Market Abuse Regulation (MAR, Article 19).
These filings are public and freely accessible. They constitute a legal information signal: a director who buys shares in their own company expresses conviction in the outlook, with their own money.
The core principle: directors sell their shares for a thousand reasons (wealth diversification, personal liquidity, tax). But they buy them for one reason only: they think the stock is undervalued. Insider purchases carry far greater informational value than sales.
Strong signals vs weak signals
🟢
Strong positive signal
Purchase > €50k by the CEO or MD. Several insiders buying in the same week. Purchase after a sharp correction with no fundamental cause. Open-market purchase (not a savings plan).
🟢
5%+ threshold crossing
An active fund or a strategic industrial buyer crosses 5% of the share capital. These players carry out thorough due diligence — their commitment is a signal of conviction.
🟡
Moderate signal
Small token purchase (< €5k). Purchase by a non-executive board member. Purchase under an incentive plan or a free-share award.
🟡
Sale by a director
To be qualified: liquidity needs, diversification, tax. Problematic only if large, coordinated across several insiders, or just before a disappointing release.
🔴
Negative signal
Several directors selling at the same time. Founder offloading a large block. Falling below a significant ownership threshold. Sales just before a results release.
🔴
Massive dilution
Dilutive capital increase with no clear use of the funds. Issuance of toxic convertible bonds — a financing mechanism unfavourable to existing shareholders.
Where to find the regulatory filings
1
National market regulator database: each regulator (e.g. the AMF in France, BaFin in Germany, the AFM in the Netherlands, CONSOB in Italy) publishes managers' transaction filings. Filterable by company, date or transaction type. The official, exhaustive source.
2
Financial platforms: these aggregate regulatory filings on each stock's page, in a "Director dealings" or "Transactions" section. A more accessible interface than the regulator's site directly.
3
The issuer's corporate website: companies are required to publish transaction filings in their investor area, under "Shareholders" or "Regulated information".
4
Official legal gazettes: national legal-announcement bulletins publish the statutory notices of listed companies, including threshold crossings.
Legal threshold crossings
Any shareholder crossing (upward or downward) certain ownership or voting-rights thresholds must disclose it to the company and the regulator within a few trading days. The typical legal thresholds are:
Threshold
Obligation
Investor signal
5%
Mandatory filing with regulator + company
Entry of a significant shareholder — strong potential signal
10%
Mandatory filing with regulator + company
Material reinforcement — analyse the stated intentions
15%
Mandatory filing with regulator + company
Potential blocking shareholder
20%
Mandatory filing with regulator + company
Possible significant influence — takeover risk or opportunity
25%
Mandatory filing with regulator + company
Blocking minority — strategic shareholder
30%
Filing + mandatory takeover-bid obligation
The takeover threshold — automatic trigger for a tender offer
33.3%
Reinforced blocking minority
Partial control position
50%
De facto control
Majority shareholder
Watch the articles of association: some Euronext Growth companies set additional statutory thresholds below 5% (e.g. 2% or 3%). Check each company's bylaws and registration documents.
A practical method for using these signals
To integrate insider signals into your investment process:
Monitor the weekly filings on the stocks in your watch universe. A meaningful purchase on a stock you know well is more actionable than one on an unfamiliar name.
Put the purchase in context: is the insider buying after a price correction? Just before a quarterly release? In which regulatory window?
Assess the relative size: a €100k purchase by a director who already holds €5M in shares is less significant than a €50k purchase by someone who held almost none.
Combine with fundamental analysis: the insider signal is a catalyst, not a sufficient reason to buy. The fundamentals must justify the position.
Regulatory monitoring built into the screener
Screener Small Caps monitors the regulatory disclosures of 800+ Euronext Growth stocks and feeds management-change signals into the ML model.
A transaction in a company's own shares carried out by a director or significant shareholder, mandatorily disclosed to the market regulator within 3 days. Insider purchases are read as a signal of confidence — they buy with their own money.
On the national market regulator's site (e.g. the AMF in France, BaFin in Germany, the AFM in the Netherlands, CONSOB in Italy), on financial aggregator platforms, or the company's own corporate website. Threshold crossings are published in official legal gazettes.
Not systematically. The most reliable signals: a purchase > €50k by an executive officer, several insiders buying at the same time, a purchase after a correction. To qualify: small token purchases, purchases under incentive plans.
Insider dealing (illegal) uses non-public information to trade. Legal insider trading is the mandatory disclosure of transactions by persons connected to the issuer, without non-public information. It is this second type that can be analysed legally.
Yes, particularly on small caps. An active fund or industrial buyer crossing 5% of the share capital after due diligence is a strong signal of conviction. Crossing 30% triggers a mandatory takeover-bid obligation.