SPY的500支股票組成 - ETF

想請問一下SPY這隻ETF的成分股
看說明就是追蹤SP500
但是我在看這個SP500 Index的說明
想了解SPY是"美國市值最大的500家"
還是有某些條件選出"最能代表美國的500家"
根據這份說明 https://us.spindices.com/documents/methodologies/methodology-sp-us-indices.pdf
The S&P U.S. indices are designed to reflect the U.S. equity markets and,
through the markets, the U.S. economy.
The S&P 500 focuses on the large-cap sector of the market; however,
since it includes a significant portion of the total value of the market,
it also represents the market.


小弟還是覺得用詞很模糊
能否有高手解答一下
謝謝

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