(Adds detail, background) SHANGHAI, Nov 12 (Reuters) - The Beijing Stock Exchange will launch trading on Monday, just two months after Chinese President Xi Jinping announced plans for the new bourse, which is designed to serve small and medium-sized enterprises (SMEs). Eighty-one companies will see their shares traded on the bourse in the first batch of listings, the exchange said in a statement, adding it was “fully ready” for the start of trading. China"s securities regulator has said the new exchange will complement existing bourses in Shanghai and Shenzhen. Investors expect a busy start to the trade in light of frothy launches of other boards, such as Shanghai"s STAR Market here in 2019. More than 2.1 million investors have newly applied to become qualified investors on the Beijing Stock Exchange, meaning more than 4 million investors will be eligible for trading, the bourse said. The exchange will employ a registration-based initial public offering (IPO) mechanism, which is only adopted by Shenzhen’s ChiNext and Shanghai’s tech-focused STAR Market currently. The Beijing bourse will serve SMEs with a focus on innovation, and contribute to high-quality growth of China’s economy, it said on Friday. The first batch of companies to be listed include 10 that were recently granted approval, as well as 71 companies transferred from the “select tier” of Beijing’s over-the-counter ‘New Third Board’, according to the statement. (Reporting by Jason Xue and Andrew Galbraith Editing by Timothy Heritage and Mark Potter)