The percentage of large-cap stocks in a diversified investment portfolio depends on an investor's investment goals, risk tolerance and time horizon.

Diversification

Diversification of an investment portfolio consists of spreading investments out into different equities and/or into different asset classes, such as stocks and bonds.

Diversification is enhanced by holding some investments that have a negative correlation with other held investments. With negatively correlated investments, an investor can reduce overall volatility and risk by virtue of the fact that some investments will perform better when other investments experience a downturn.

A classic diversified portfolio consists of a mix of approximately 60% stocks and 40% bonds. A more conservative portfolio would reverse those percentages. Investors may also consider diversifying by including other asset classes, such as futures, real estate or forex investments.

An investor's age also plays an important role in diversification. Individuals closer to retirement may prefer a more conservative portfolio and look to increase their bond allocation, whereas investors who are much younger can tolerate more risk in their portfolio and therefore choose riskier, higher return investments.

Diversification Within Equity Investments

Beyond simply a mix of stocks and bonds, diversification can be further enhanced through an investor holding a combination of large-, mid-, small- or micro-cap stocks.

Large-cap stocks are companies whose market capitalization is $10 billion or higher. They are generally considered safer investments, since they typically represent large, well-established companies that are expected to continue as profitable businesses. However, large-cap stocks usually offer less potential for high growth than mid- or small-cap companies as they already make up a large part of the market share, and as such, growth opportunities are smaller.

This is not always the case, though, as some large-cap firms, such as Google or Amazon, still offer high growth because of their presence in high-growth market sectors. Smaller market cap stocks usually come with both higher growth potential and higher risk levels. They have the opportunity to capture more market share but are also more susceptible to market fluctuations.

Large-cap companies also offer dividend payouts, which can make a large-cap stock more attractive, generating higher overall returns for an investor.

The optimal mix in equities that an investor chooses is ultimately guided by individual investment goals and risk tolerance. Investors aiming for higher returns and willing to accept higher risk typically devote more of their portfolio to mid- and small-cap stocks, while more conservative investors maintain a higher percentage of large-cap stocks.