El precio indexado cambia en el mercado libre.

In Spanish, the definite article is often used where English might omit the.

Here, el precio means the price. Saying Precio indexado cambia... would sound incomplete or unnatural in normal Spanish.

Spanish usually prefers an article with a singular countable noun like precio, especially when talking about it as a general concept within a specific context.

In Spanish, descriptive adjectives normally come after the noun.

So:

• el precio indexado = the indexed price

This is the most natural order. Putting the adjective before the noun is sometimes possible in Spanish, but it often changes the tone or sounds literary, emphatic, or unusual. In this sentence, precio indexado is the standard order.

Indexado is the past participle of indexar, and here it is being used like an adjective.

So precio indexado means something like:

• indexed price
• price linked to an index
• price that varies according to a reference value

Grammatically, it behaves like an adjective, so it has to agree with the noun:

• el precio indexado — masculine singular
• la tarifa indexada — feminine singular
• los precios indexados — masculine plural

Because the subject is el precio indexado, which is third person singular.

So the verb must also be singular:

• el precio indexado cambia = the indexed price changes

Compare:

• el precio cambia = the price changes
• los precios cambian = the prices change

And cambiar is the infinitive, meaning to change, so it would not work here as the main conjugated verb.

The present tense in Spanish is often used for:

• general truths
• regular behaviour
• things that happen habitually

So cambia here suggests that this price changes or varies as a normal characteristic of the free market.

It does not necessarily mean it is changing right this second. It can mean it changes / it varies in general.

En is the normal preposition here because it means in or within the context of that market.

So:

• en el mercado libre = in the free market

It tells you the setting or context in which the price changes.

Using a would not work here, because a usually marks direction, destination, or certain objects, not the environment where something happens.

Because mercado is a singular masculine noun, and here it refers to the free market as a specific concept.

So:

• en + el = en el

Unlike a + el, which contracts to al, en + el does not contract in Spanish. It simply stays en el.

No. Here libre means free in the sense of open, unrestricted, not regulated in the same way, not free of cost.

So mercado libre means:

• free market
• open market

It does not mean that things cost nothing there.

It can be both.

Literally, mercado libre means free market. But in Spain, especially in energy-related contexts, mercado libre often contrasts with a regulated market.

So in a real-life Spanish context, this sentence may suggest a specific economic or energy-market distinction, not just a general idea of a free market.

Yes, but it would mean something slightly different.

• El precio indexado cambia en el mercado libre = the indexed price changes / varies in the free market
• El precio indexado está cambiando en el mercado libre = the indexed price is changing in the free market

The original sentence sounds more general and factual.
The estar + gerundio version focuses more on a change happening right now or around the present moment.

In standard Peninsular Spanish:

• precio is roughly PRE-thyo
• cambia is roughly KAM-bya

A few useful notes:

• In Spain, c before e or i is often pronounced like th in think
• ca is pronounced with a hard k sound
• ia in cambia forms a smooth glide, so it sounds like bya, not bee-a

Yes. Spanish often drops subject pronouns, but not usually the main noun subject if that noun contains important information.

You could say:

• Cambia en el mercado libre

But that would mean It changes in the free market, and the subject would have to be understood from context.

In the original sentence, El precio indexado is kept because it tells you exactly what changes.

It is understandable, but it sounds more technical, economic, or administrative than everyday casual speech.

You are more likely to see indexado in contexts like:

• finance
• pricing
• contracts
• energy bills
• economics

So the sentence sounds fairly formal or specialized, not especially conversational.