It is possible to gain insight into broader market trends and investor sentiment by analyzing the market for ETFs in the United States, with an emphasis on ETFs that track the S&P 500 index. An analysis of various aspects is provided here:

Performance:

1. Historical Performance: Tracking the historical performance of S&P 500 ETFs is useful in grasping the investors’ implicit view of how well the market performed within a set timeframe. It refers to examining not only the periodic movements and but also the time factors behind the patterns.

2. Relative Performance: If, for example, we look at the performance of S&P500 ETFs we shall notice how more effective fund manager promotes tracking precision, the lower expense ratio they have, and vice versa.

Composition:

1. Weighting Methodology: Establishing the way in which the cap is weighed (e.g., marketcap, equalweight) is of equal importance. Consequently, this determines the amount of investor’s exposure to individual companies within the index. This in turn involves their ability to diversify their portfolios through multiple investments.

2. Sector Allocation: Investment allocation analysis of S&P 500 ETFs will bring out market trends and modes of thinking of the investor about industries or sectors, a particular fact people showed interest in.

Fundamentals:

1. Expense Ratios: We should mention expense ratio, because somewhat low expense ratio can result in higher return, and is also appealing for long-term investors.

2. Liquidity: The liquidity of S&P 500 ETFs is one of the essential factors that should be brought under consideration by any investor who is seeking to acquire or shed off shares.

Market Sentiment:

1. Investor Flows: Whether in the inflows or outflows of investment, ETF tracking S&P 500 provides useful information about the market mood and the behavior of investors.

2. Options Trading: Options trading on S&P 500 ETFs can be used as source to show the general trends of market expectations as well as investors' sentiment for the expected future prices.

Economic Indicators:

1. Interest Rates: An increase in interest rates could lead in the degradation of ETFs performance of S&P 500 as it's higher interest rates diminishes borrowing costs, earnings and investor sentiment.

2. Inflation: Inflation can create sentiments among investors and revaluation of the market which has the power to affect the functioning of S&P 500 ETFs shares.

Geopolitical Factors:

1. Trade Policy: An alteration of trade legislation and growth in the geopolitical tensions could affect the markets on a global scale, comprising the S&P 500 ETF performance.

2. Regulatory Environment: Regulatory changes might determine how the firms within the S&P 500 work and the amount of their profitability, and thus change ETF efficiency.

Risk Factors:

1. Market Volatility: Measuring historical and resultant implied volatility via options market instruments may aid investors in estimating the risk level in S&P 500 ETF purchases.

2. Systemic Risks: The fact, that we look at the systematic risks (like economic stagnation, geopolitical crisis, financial market calamity) is of prime importance when it comes the downside risk evaluation and investing in S & P 500 ETFs.