Output restriction, also known as production restraint or quota fixing, is a form of market manipulation where two or more parties agree to limit the quantity of trades, production, or supply of a security or commodity to influence market prices. This can include:

1. _Production quotas_: Agreeing to limit production levels to restrict supply.

2. _Trade quotas_: Agreeing to limit the quantity of trades to manipulate prices.

3. _Supply restrictions_: Agreeing to limit the supply of a security or commodity.

4. _Output curtailment_: Agreeing to reduce or halt production to influence prices.

Output restriction can lead to:

1. _Artificial price inflation_: Reducing supply to drive up prices.

2. _Market imbalance_: Disrupting the natural supply and demand balance.

3. _Reduced competition_: Limiting market access and stifling innovation.

4. _Harm to investors_: Causing financial losses for unsuspecting investors.

5. _Undermining market integrity_: Eroding trust in the market and its participants.

To detect and prevent output restriction, regulators and exchanges use:

1. _Trade surveillance_: Monitoring trading activity for suspicious patterns.

2. _Market monitoring_: Analyzing market data for unusual activity.

3. _Investigations_: Conducting in-depth analyses of suspected output restriction.

4. _Whistleblower tips_: Encouraging reporting of suspicious activity.

5. _Regulatory enforcement_: Imposing penalties and fines for output restriction violations.

Output restriction is a form of collusion, and regulators and exchanges take measures to prevent and detect such activities to maintain fair and orderly markets.