American Depositary Receipts or ADRs. These are shares of foreign companies listed on exchanges in the USA in dollars.

They allow US investors to get access to overseas shares without the hassle of having to exchange currency, open brokerage accounts overseas and so on.

Asset-backed securities.

These are securities backed by assets, like mortgages, which are claimable if the creditor defaults.

When the majority of shares changes hands in a company.

This is typically when one company buys another.