Unrestrained Capacity
The credit market is a deep pool of trillions of dollars of liquid debt. Since the principle of the investment rests in this market, capacity contraints are non-existent. If an investor chooses to capture rewards in the S&P index, there are a variety of different vehicles that can be used to accomplish this, and liquidity is constrained to ~$500 billion in a given month, though larger size could be facilitated. In other capture vehicles such as select sector ETFs, REITs, etc., the capture liquidity is lower.