Because there are two separate controllers in each USB 3.0 host, USB 3.0 devices transmit and receive at USB 3.0 data rates regardless of USB 2.0 or earlier devices connected to that host. Operating data rates for earlier devices are set in the legacy manner.
The Dow Jones Industrial average (DJIA) and NASDAQ Composite Index are indexes that track the movement of a number of different stocks. The DJIA is made of companies that are traded on the New York Stock Exchange while the NASDAQ index is composed of companies that are traded on the NASDAQ stock exchange.
The NASDAQ Composite (^IXIC) is a stock market index of the common stocks and similar securities (e.g. ADRs, tracking stocks, limited partnership interests) listed on the NASDAQ stock market. Along with the Dow Jones Average and S&P 500 it is one of the three most-followed indices in US stock markets.