to swap for a stock market index return in exchange for another source of return, typically a fixed income or money market return. Swap contracts exposure investors to counterparty credit risk, low liquidity risk, interest rate risk, and tax policy risk. However, swap contracts can be negotiated for whatever index the parties agree to use as underlying index, and for however long the parties agree to set the contract, so investors could potentially negotiate swaps more compatible with their investment needs than funds, ETFs, and futures contracts. Implementation methods Full replication in index investing means that manager holds all securities represented by the index in weights that closely match the index weights. Full replication is easy to comprehend and explain to investors, and mechanically tracks the index performance. However, full replication requires that all the index components have sufficient investment capacity and liquidity, and that the assets under investment management is large enough to make investments in all components of the index. Stratified sampling in index investing means that managers hold sub-sets of securities sampled from distinct sub-groups, or strata, of stocks in the index. The various strata imposed on the index should be mutually exclusive, exhaustive (sum to make up the whole index), and reflective of the characteristics and performance of the entire index. Common stratification techniques include industrial sector membership (such as sector membership defined by Global Industry Classification Standard (GICS)), equity style characteristics, and country affiliation. Sampling within each strata could be based on minimum market-cap criteria, or other criteria that mimics the weighting scheme of the index. Optimization sampling in index investing means that managers hold a sub-set of securities generated from an optimization process that minimizes the index tracking error of a portfolio subject to constraints. These sub-sets of securities do not have to adhere to common stock sub-groups. Common constraints include the number of securities, market-cap limits, stock liquidity, and stock lot size. Globally diversified portfolios of index funds are used by investment advisors who invest passively for their clients based on the principle that underperforming markets will be balanced by other markets that outperform. A Loring Ward report in Advisor Perspectives showed how international diversification worked over the 10-year period from 2000–2010, with the Morgan Stanley Capital Index for emerging markets generating ten-year returns of 154% balancing the S&P 500 index, which declined 9.1% over the same period – a historically rare event.