Default risk is the risk that arises when the issuer is not able to satisfy the terms and conditions of the obligation with respect to timely payment of interest and repayment of the amount borrowed. If a default occurs, the investor does not lose the entire amount invested as he can recover a certain percentage of the investment. This is called recovery rate. The percentage of a population of bonds that is expected to default is called default rate. Given the default rate and the recovery rate, the estimated expected loss due to a default can be computed.

Default risk is associated with corporate bonds unlike treasury bonds since there is a risk of non-payment of principal and interests either partially or fully due to several factors.

The difference between the investor's expected rate of return and the actual rate of return offered is known as risk premium. This includes the risk associated with a particular bond depending on the likelihood of default either partially or fully. This risk premium depends on the issuer's financial position and fundamentals. Normally, credit rating agencies rate the companies  for their issues on the basis of certain factors like capital structure, leverage ratio, earnings ratio, current ratio, the performance of the particular industry, etc., by giving necessary weightages to evolve the rating for the companies. Rating agencies like S&P, Moody's, CRISIL, ICRA, etc., give credit ratings for the issuing company. Companies with higher rating will have lesser default possibility compared to the companies with lesser ratings.