Derivatives: what they are, how risky they are and how they are taxed

A derivative is a contract whose value depends on another asset (the underlying): a stock, an index, a commodity, a currency… You do not buy the company or the index; you buy a contract that gains or loses as the underlying moves. They are used to hedge a risk or to speculate, and almost always with leverage.

The most common ones

Futures: an agreement to buy or sell an asset at a fixed price on a future date. They are settled daily by differences.
Options: give the right (not the obligation) to buy (call) or sell (put) at a given price and date. The buyer pays a premium that can be lost entirely.
Warrants: options issued by a financial institution and traded on a market as if they were a security.
Knock-outs and turbos: leveraged products that are cancelled if the underlying touches a level (the barrier); when that happens, what you invested is lost (or nearly).
CFDs (contracts for difference): you receive or pay the difference in the underlying's price between opening and closing, without ever owning it.

Leverage: winning and losing faster

Leverage lets you control a position larger than the money you put in. At 10×, a 5% rise in the underlying gives 50% on what you invested... and a 5% fall gives −50%. With a knock-out barrier, a moderate fall is enough to lose 100% of what you invested. With some products (futures, CFDs, written options) you can even lose more than you put in.

That is why they are products for people who understand exactly what they are buying: they are not a "faster" alternative to an index fund, but a different kind of risk. See also diversification and risk.

How they are taxed in Spain

In general terms, the result of buying and selling derivatives is a capital gain or loss that goes into the savings base: the year's gains and losses are added up, can offset each other, and the balance is taxed at the savings brackets (19% to 30%). Net losses are carried forward for four years, as the guide on capital gains when you sell explains. Some specific products (some settled as interest, or held for hedging) have their own treatment, so check each one.

The two-month rule. The rule that blocks a loss if you buy back the same security within two months before or after is written for securities and participations. The doctrine of the tax authority's General Directorate (for example, binding ruling V2172-21, on options) holds that derivatives such as futures and options are financial instruments, not negotiable securities, so that rule does not apply to them. The same reasoning is usually applied to CFDs, but check it for your own case. Warrants, turbos and certificates trade as securities, and there the answer depends on the specific product and on whether there are homogeneous securities: do not assume either way, and ask.

Derivatives with a foreign underlying or broker can also bring reporting obligations (for example, declaring assets and rights abroad). Check your case before filing your return.

Why Sextante does not track their price

Sextante records your derivatives (for example, those you import from Trade Republic) with their buys and sells, and they count in the capital gains report. But it does not track their price: a knock-out or a warrant has its own identifier, expires, gets cancelled, and its quote depends on issuer, barrier and maturity, something the price sources we use do not cover reliably. A missing or wrong quote would distort your returns, so in the portfolio they sit in a separate, collapsed section and do not add to the totals or the market value.

Educational information, not financial or tax advice. Derivatives can make you lose everything you invested, or more. The rules and their interpretation change; check your case with the tax agency or an adviser.