Interest rates and USD strength are positively correlated.
An increase in US interest rates will typically result in a strengthening of the USD.
The reason is...
Foreign investors tend to flock to US assets, such as bonds and fixed bank rates for higher returns.
Higher demand for US assets drives up their price, and as a result, the USD strengthens.
As for the relationship between USD strength and US stock market prices, it is more complex and can have both positive and negative effects.
On one hand, a strong USD can make US exports less competitive, reducing demand and potentially leading to a decrease in corporate profits.
This can weigh on stock prices. On the other hand, a strong USD can attract foreign investment into US stocks, driving up demand and prices.
There are other reasons for the correlation such as:
Interest rate differentials
When interest rates in one country are higher than in another, capital tends to flow to the country with the higher interest rates.
This results in an increase in demand for the currency of the country with higher interest rates, strengthening its currency i.e US Dollar.
Inflation expectations
Interest rates are also closely linked to inflation expectations.
When interest rates rise, it is generally expected that inflation will rise too, which makes the currency more attractive to investors.
Trade flows
The USD is the currency used in most international trade transactions, and as a result, changes in trade flows can have a significant impact on the value of the USD.