An investment strategy or portfolio is considered market-neutral if it seeks to entirely avoid some form of market risk, typically by hedging. In order to evaluate market-neutrality, it is first necessary to specify the risk being avoided. For example, convertible arbitrage attempts to fully hedge fluctuations in the price of the underlying common stock. A portfolio is truly market-neutral if it exhibits zero correlation with the unwanted source of risk. Market neutrality is an ideal, which is seldom possible in practice. A portfolio which appears to be market-neutral may exhibit unexpected correlations as market conditions change. The risk of this occurring is called basis risk. Equity-market-neutral
Equity-market-neutral is a hedge fund strategy that seeks to exploit investment opportunities unique to some specific group of stocks while maintaining a neutral exposure to broad groups of stocks defined, for example, by sector, industry, market capitalization, country, or region. The strategy holds long/short equity positions, with long positions hedged with short positions in the same and related sectors, so that the equity-market-neutral investor should be little affected by sector-wide events. This places, in essence, a bet that the long positions will outperform their sectors (or the short positions will underperform) regardless of the strength of the sectors. Equity-market-neutral strategy occupies a distinct place in the hedge fund landscape by exhibiting one of the lowest correlations with other alternative strategies. Evaluating the Hedge Fund Research index returns for 28 different strategies from January 2005 to April 2009 showed that equity-market-neutral strategy had the second lowest correlation with any of the other strategies, behind only short-bias funds that typically have a negative correlation with all other funds. This result is not surprising given that each fund utilizes the unique insights of a manager, and these insights are not replicated across funds. •Delta neutral
In finance, delta neutral describes a portfolio of related financial securities, in which the portfolio value remains unchanged due to small changes in the value of the underlying security. Such a portfolio typically contains options and their corresponding underlying securities such that positive and negative delta components offset, resulting in the portfolio's value being relatively insensitive to changes in the value of the underlying security. A related term, delta hedging is the process of setting or keeping the delta of a portfolio as close to zero as possible. In practice, maintaining a zero delta is very complex because there are risks associated with re-hedging on large movements in the underlying stock's price, and research indicates portfolios tend to have lower cash flows if re-hedged too frequently. Nomenclature
The sensitivity of an option's value to a change in the underlying stock's price. The initial value of the option.
The current value of the option.
The initial value of the underlying stock.
Main article: Greeks (finance)
Delta measures the sensitivity of the value of an option to changes in the price of the underlying stock assuming all other variables remain unchanged. Mathematically, delta is represented as partial derivative of the option's fair value with respect to the price of the underlying security. Delta is clearly a function of S, however Delta is also a function of Strike Price and time to expiry.  Therefore, if a position is delta neutral (or, instantaneously delta-hedged) its instantaneous change in value, for an infinitesimal change in the value of the underlying security, will be zero; see Hedge (finance). Since delta measures the exposure of a derivative to changes in the value of the underlying, a portfolio that is delta neutral is effectively hedged. That is, its overall value will...