Where you are. You can compute what a holding entitles you to and pay a dividend through it. This lesson asks where the holding physically is. The answer repeats a shape you already know: your share, like your deposit, is a claim on somebody who holds a claim on somebody else, and the company’s own list of owners does not have your name on it.
Ask your broker for your share certificate
You bought ten shares. The app shows ten shares. Ask where they are.
They are not in the app; the app is a view onto your broker’s records. They are not in your name at the company either. If you rang the company’s registrar and asked how many shares you own, the honest answer would be none: your name does not appear on the register at all.
What appears on the register is a single line, holding a large block of shares in the name of a nominee. Behind that one line sit thousands of brokers, and behind those brokers sit millions of people who each believe, correctly enough for daily purposes, that they own shares.
The idea in one paragraph
Share ownership is recorded in a chain, and each link records a claim on the link above rather than the asset itself. At the top, the company’s registrar names one holder for the market’s whole block: a nominee at a central securities depository. The depository records how much of that block belongs to each broker. Each broker records how much of its holding belongs to each customer. You are at the bottom, holding an entitlement against your broker, which holds an entitlement recorded at the depository, which is the name on the company’s register. This is exactly the two-tier pattern from module 0 with more tiers: what you hold is a claim on a claim, and the thing itself sits at the top, immobile.
Wider than the screen; scroll it sideways.
What a trade actually moves
Now buy ten shares from somebody who banks, so to speak, at a different broker.
At the bottom, two entries change: the seller’s entitlement at their broker falls by ten, and yours at your broker rises by ten. One level up, the depository moves ten from the seller’s broker to yours, because the blocks each broker is entitled to have shifted.
And the registrar does nothing at all. The company’s own list is unchanged, because the nominee still holds exactly the same total. From the company’s point of view, nothing happened.
If both customers happen to use the same broker, even the depository sits still: the trade is a change of two lines inside one broker’s own book, and nothing above it moves. That is the same insight module 2 gave you about wallets and overlays, one layer up: the fewer ledgers a transfer must cross, the less machinery it needs.
Why anyone built it this way
Because the alternative was paper, and paper nearly killed the market. Certificates had to be found, checked, physically carried between brokers and re-registered in the buyer’s name for every trade, and when volumes rose the settlement machinery simply could not keep up. Immobilising the certificates in one place and settling by book entry is what made high volumes possible at all.
The cost is the one you have just traced: you are several claims away from the thing you own.
Check yourself
1. You own ten shares. Whose records say so, and whose do not?
Your broker’s records say you are entitled to ten. The depository’s records say your broker is entitled to some larger number that includes your ten. The company’s register says the nominee holds the whole block and says nothing about you at all. You are a claim on a claim on the registered holding.
2. A trade settles between customers of two different brokers. Which levels of the chain change, and why is the registrar untouched?
The two brokers’ customer records change, and the depository moves the block between the two brokers. The registrar is untouched because the nominee’s total holding is the same as it was: shares moved inside the nominee’s block, not into or out of it.
3. Why does a trade between two customers of the SAME broker not reach the depository at all?
Because the broker’s own entitlement at the depository has not changed. Both sides of the trade are inside its book, so the only records that must move are the two customer lines it keeps itself. The trade never becomes visible to the level above.
4. What does this chain have in common with the two-tier money map from module 0?
Both record ownership as claims on claims, with the real thing immobilised at the top and everyone below holding an entitlement against the layer above. Your deposit is a claim on a bank that holds reserves at the central bank; your share is a claim on a broker that holds an entitlement at the depository. The question to ask of both is the same: whose liability is what I am holding?
Do this
Settle a trade down the chain and prove the registrar never moves.
python3 code/custody_chain.pyThe starter leaves you settle_trade, which must move the customer entitlements at the two brokers, move the block between brokers at the depository, and touch the registrar not at all. The assertions check each of those, including that all three levels still add to the same block afterwards. Success prints the four ledgers and the line:
you own an entitlement against your broker, not a line in the company's own book: two ledgers changed, and neither was the company'sThe completed version is in solutions/custody_chain.py.
What you can now do. You can trace a share from a company’s register down to a customer’s app, name each institution in the chain, and say which records a trade touches and which it leaves alone. The next lesson takes the same chain and pushes something down it in the other direction: an event that happens to the shares themselves, which every layer must process correctly or somebody ends up short.