• Day trading: Buying and selling stocks, currencies, or other financial instruments within the same trading day, aiming to profit from small price fluctuations.
• Short selling: Borrowing shares of a company and selling them, with the expectation of buying them back later at a lower price to profit from a decline in the share price.
• Commodity speculation: Trading in commodity futures or options, such as oil, gold, or agricultural products, with the goal of profiting from changes in their prices.
• Currency speculation: Buying and selling currencies in the foreign exchange market, betting on the appreciation or depreciation of one currency against another.
• High-frequency trading: Using sophisticated algorithms and high-speed computers to execute large numbers of trades in milliseconds, profiting from small price differences or market inefficiencies.

Speculation can play a role in providing liquidity and price discovery in financial markets, but it can also contribute to market volatility, bubbles, and financial crises when excessive or unbalanced. Regulators and policymakers often aim to balance the benefits of speculation with the need for market stability and the protection of investors and the broader economy.

This is a risky action in which a person or organisation tries to predict what will happen to the price of an asset and buys / sells accordingly in order to try and make a profit. A speculator takes advantage of fluctuations in market prices.