Sponsored Access refers to the practice in which a bank or brokerage firm offers a client direct market access to an exchange without any pre-trade risk management present. Sponsored access allows high frequency traders to access low-latency markets with pre-execution controls provided by the exchange.
Sponsored access has many different meanings for market participants, and is often misunderstood. Its origin can be traced back to the practice of direct market access (DMA), in which a broker who is a member of an exchange provides its market participant identification (MPID) and exchange connectivity infrastructure to a customer interested in sending orders directly to the exchange.
In a December 2009 report on sponsored access, Aite Group defined it as when a non-member entity (i.e., a sponsored participant) gains direct access to market centers by using the MPID of a member broker/dealer, leveraging access infrastructure not owned by the sponsoring broker.
Firms may decide to go through a sponsored access arrangement for many reasons, including reduced latency, additional revenue opportunities, and hitting volume discounts. 
- Sponsored access and DMA: Predicting the next blow up. Euromoney.
- Sponsored Access Comes of Age. Traders Magazine.
- Nasdaq Nordic offers Sponsored Access for both cash equity and derivatives markets members. Nasdaq.
- Sponsored Access. London Stock Exchange Group.
- Direct Market Access, Naked Access, Electronic Access or Sponsored Access ("DMA"). FINRA.
- Sponsored Access: Where the Naked Need Not Apply. Advanced Trading.