The Massachusetts Investment Sentiment Index (MISI) is a market based measure of investor sentiment for firms that are either headquartered in Massachusetts or have a significant presence in the state. The MISI is constructed using firms that are in the Massachusetts Bloomberg Index (BBMX), which follows 240-250 firms which span more than 50 industries and range in size from $2 million to $42 billion in market capitalization. Daily returns for each of the securities in the BBMX and the average standard deviation of daily returns over the previous five days (the "historic volatility") are computed. The MISI is constructed every day using a correlation of the daily returns and the historic volatility.

The MISI can range from a low of -100 to a high of +100. For values between -10 to +10 the market is classified as risk-neutral, for values between -10 and -30 the market is labeled moderately risk-averse, and for values less than -30 the market is considered highly risk-averse. Similarly, if MISI falls between +10 and +30, the market is labeled moderately risk-seeking, and if the index exceeds +30, the market is considered highly risk-seeking.

Movements in the MISI capture both positive and negative news concerning Massachusetts firms and the region's economy. Also, changes in the MISI closely replicate changes in the BBMX. The MISI and the BBMX return for the same trading day has, on average, a significant correlation coefficient of about seventy-five percent.