The full form of MTNs is Medium-Term Notes

A medium-term note (MTN) is a debt note that usually matures (is paid back) in 5–10 years, but the term may be less than one year or as long as 100 years. They can be issued on a fixed or floating coupon basis. In opposite to conventional bonds, these can be offered continuously through various brokers, instead of issuing the full amount at once. Also, in contrast to conventional bonds market, the agent (typically investment bank) in MTM market is not obliged to underwrite the notes for the issuer and the agent is thus not guaranteed funds. Floating rate medium-term notes can be as simple as paying the holder a coupon linked to Euribor +/- basis points or can be more complex structured notes linked, for example, to swap rates, treasuries, indices, etc. The amount of the issues usually ranges from $100 million to $1 billion. In the recent years, MTNs have become major source of financing in international financial markets, both in US and EU.