Deep Analysis of the US Dollar Index: A Key Indicator Affecting Global Investments

The US Dollar Index (USDX) plays a key role in the global financial markets, not only reflecting the strength or weakness of the dollar but also directly influencing the price movement of various asset classes. As the US Dollar Index falls to 97.7145 in October 2025, investors need to gain a deeper understanding of the workings of this indicator and its impacts.

Basic Concept of the USD Index

The US Dollar Index (USDX or DXY) is a composite indicator that tracks the changes in the exchange rate of the dollar against six major international currencies. Similar to the “S&P 500” and the “Dow Jones Index” in the stock market, the US Dollar Index is also an index that tracks the performance of a specific asset, but it measures the relative strength of the dollar against other important currencies.

The six currencies included in the US Dollar Index and their weight distribution:

These six currencies represent not only six countries but also more than 24 developed economies. Among them, the Eurozone includes 19 EU countries, which is why the US dollar index holds such high reference value and influence in the global financial market.

Calculation Method of the USD Index

The US Dollar Index is calculated using a “geometric weighted average” method, which means that different weights are assigned to each currency based on its economic size and international trading influence. The US Dollar Index is measured relative to the benchmark value set in March 1973:

• Index = 100: Indicates parity with the base period, and the strength of the US dollar remains unchanged.
• Index < 100: Indicates that the USD is weaker compared to the benchmark period.
• Index > 100: Indicates that the USD is stronger than the benchmark period.

Therefore, the higher the index value, the stronger the US dollar in the international market; the lower the value, the weaker the US dollar relative to others.

Market Significance of the Fluctuations in the USD Index

The impact of the rise in the USD Index (strengthening of the USD)

When the US Dollar Index rises, it represents an appreciation of the dollar against major international currencies, which will bring a series of economic and market effects:

Impact on the US Economy:

• The cost of imported goods has decreased, which is beneficial for controlling inflation.
• Attract international capital inflow into the US market, especially the US Treasury bond market.
• The purchasing power of American consumers has strengthened, allowing them to buy imported goods with fewer dollars.

Impact on the global market:

• International commodities priced in USD (such as crude oil and gold) become relatively more expensive for other countries.
• The dollar debt burden of emerging market countries has increased, leading to greater repayment pressure.
• The export competitiveness of export-oriented economies (such as Taiwan and South Korea) may decline.

The impact of the fall in the USD index (weakening of the dollar)

When the USD index falls, it indicates that the USD is depreciating relative to other major currencies:

Impact on Global Capital Flow:

• Funds may flow from the U.S. market to Asian stock markets or emerging markets.
• International investors may reduce their holdings of USD assets and shift towards other currency assets.

Impact on Different Regions:

• Beneficial for export-oriented economies, as their export products are more competitive in the U.S. market.
• Investors holding USD assets may face exchange rate losses.
• The New Taiwan Dollar and other Asian currencies may appreciate, affecting the trade competitiveness of the region.

Impact on the Commodity Market:

• Products priced in USD (such as gold, crude oil) usually rise.
• The international competitiveness of domestic manufacturers in the United States has strengthened, helping to improve the trade deficit.

Correlation Between the USD Index and Major Asset Classes

USD index and stock market

The relationship between the USD index and the stock market is relatively complex and can vary depending on different market environments:

• In some cases, a stronger USD rises in sync with US stocks, especially when a strong USD reflects a robust US economy or heightened global risk aversion.
• In other circumstances, an excessively strong USD may suppress the overseas earnings of American companies, especially those multinational corporations that rely on exports or have significant overseas income.

Taking March 2020 as an example, at that time the global stock market crashed due to the pandemic, but the USD index rose to 103 points due to safe-haven demand. Subsequently, the Federal Reserve implemented quantitative easing policies, and the USD index quickly fell back to 93.78.

USD index and gold

The USD and gold usually show an inverse relationship:

• When the USD strengthens, the price of gold often falls.
• When the USD weakens, the price of gold often rises.

This inverse relationship is mainly because gold is priced in USD. When the USD appreciates, the same value of gold requires fewer USD to purchase, which reduces the nominal price of gold. However, gold prices are also influenced by factors such as inflation expectations, geopolitical risks, and overall market sentiment.

USD index and cryptocurrency market

The relationship between cryptocurrency and the USD index also shows a certain correlation:

• When the USD strengthens, the prices of major cryptocurrencies such as Bitcoin are usually under pressure.
• When the USD weakens, the cryptocurrency market often sees capital inflows and price increases.

Investors often refer to the USD index price movement as one of the important indicators for determining market direction when trading crypto assets on mainstream trading platforms.

Key Factors Affecting the Fluctuation of the USD Index

The fluctuations of the USD Index are influenced by various factors, and here are some of the main driving factors:

Federal Reserve (Fed) monetary policy

The Federal Reserve's interest rate policy is the most direct factor affecting the USD index:

• Interest rate hike cycle: Raising interest rates typically attracts international capital inflow into the United States, driving up the value of the USD.
• Interest Rate Cut Cycle: Lowering interest rates often leads to capital outflows from the United States, weakening the USD.
• Quantitative Easing/Tightening: Expanding the balance sheet (printing money) usually weakens the dollar; shrinking the balance sheet supports the dollar.

According to the latest data, the weakening of the USD in October 2025 is closely related to the market's expectations of an impending interest rate cut by the Federal Reserve.

economic data performance

Key economic indicators have a significant impact on the USD price movement:

• Employment Data: Strong non-farm employment data usually supports the USD; an increase in the unemployment rate is bearish for the USD.
• Inflation Data: An increase in CPI may prompt the Federal Reserve to adopt tightening policies, supporting a stronger USD.
• GDP Growth: Economic growth exceeding expectations is usually favorable for the USD.

The fall of the US dollar index in 2025 is partly influenced by the weak job market and rising unemployment rate in the United States.

Geopolitics and International Events

Geopolitical factors often trigger market risk aversion:

• Political Uncertainty: Major political events such as elections and government transitions
• Trade Policy: Tariff adjustments, trade agreements, etc.
• International Conflicts: War, sanctions, or regional tensions

It is worth noting that the US dollar is traditionally seen as a safe-haven asset and usually gains support during times of global uncertainty.

Performance of other major currencies

Since the US dollar index is a relative indicator, the independent performance of other currencies will also affect the index movement:

• The policy changes of the Euro (which has the largest share) have a significant impact on the USD index.
• The Bank of Japan's policy shift may lead to fluctuations in the yen, which in turn affects the USD index.
• UK economic data and the Bank of England's policies are also important factors.

The latest price movement of the USD index

According to the latest data, as of October 3, 2025, the US Dollar Index (DXY) fell to 97.7145, down 0.13% from the previous trading day, and has cumulatively fallen 0.64% over the past month. Although the index is still above the levels seen at the beginning of 2023, it is significantly lower than the levels in February 2025.

The main driving factors behind the recent USD weakness include:

• The U.S. labor market data is weak, and the unemployment rate is rising.
• The market expects the Federal Reserve to further cut interest rates in the coming months.
• Concerns about the independence of the Federal Reserve and the sustainability of U.S. fiscal policy are increasing.
• The U.S. economic growth forecast for 2025 has been downgraded from 2.3% at the beginning of the year to 1.4%, although there has been a slight recent rebound.

Investors should closely monitor changes in these factors on mainstream trading platforms, as they will continue to affect the future price movement of the USD index, thereby influencing the performance of various global assets.

USD Index Trading and Investment Applications

Understanding the significance of the USD index for investment decisions:

• Diversified Investment Portfolio: When the USD is strong, consider increasing the allocation to USD assets; conversely, consider increasing other currency assets.
• Commodity Investment Strategy: When the USD weakens, it is advisable to pay attention to commodities such as gold and crude oil.
• Foreign Exchange Trading Reference: The US Dollar Index is an important indicator for assessing the price movement of the US dollar against other currencies.
• Risk management tools: Hedge portfolio risks through USD index futures or options.

For investors holding international assets, understanding the fluctuations of the USD index and its impact on different asset classes is the foundation for developing a comprehensive investment strategy.

The Difference Between the Trade-Weighted U.S. Dollar Index and the U.S. Dollar Index

Many investors confuse the US Dollar Index (USDX) with the US Dollar Trade Weighted Index, but there are clear distinctions between the two:

• US Dollar Index (USDX): Only includes six major currencies, calculated with fixed weights, primarily reflecting the performance of the dollar against the currencies of developed economies.
• US Dollar Trade-Weighted Index: Includes currencies from more countries and regions, with weights dynamically adjusted based on the trade volume between the US and each country, providing a more comprehensive reflection of the actual purchasing power of the dollar.

For investors focusing on specific markets, it is particularly important to choose the right indicators to track the USD price movement.

The US dollar index is one of the core indicators of the global financial market. Understanding its operating mechanism and influencing factors can help investors better grasp the market pulse and make more informed investment decisions, whether investing in stocks, bonds, commodities, or cryptocurrencies.