NEW YORK CITY, New York: Tesla shares closed 4 percent higher on June 9 after General Motors joined Ford in agreeing to use Tesla's electric-vehicle charging network.

This partnership among three major US automakers is seen as a significant win that could establish Tesla Superchargers as the industry standard in the United States.

The collaboration ensures that over 60 percent of the country's EV market can access Tesla's North American Charging Standard, making it the primary network nationwide.

The White House announced that electric-vehicle charging stations using Tesla's standard plugs would be eligible for federal subsidies, as long as they include the US charging standard connection, CCS.

Shares of independent charging companies, such as ChargePoint Holdings, EVgo, and Blink Charging, closed between 11 and 13 percent lower in response to the news, as Tesla opening up its Supercharger network to competitors is viewed as a negative for third-party charging companies.

Wedbush Securities estimates that Ford and GM's involvement could generate some $3 billion in EV charging revenue for Tesla over the next few years. The firm increased its price target for Tesla stock to $300, nearly 30 percent above its last close.

Since announcing the charging partnership with Ford on May 25, Tesla has added about $190 billion to its market value, solidifying its position as the world's most valuable automaker.

Tesla's stock has closed higher for the eleventh consecutive session, marking its longest winning streak in 2-1/2 years. It also remains one of the most actively traded stocks on US exchanges.

With a forward 12-month price-to-earnings ratio of 60.46, Tesla's valuation far surpasses that of GM and Ford within the S&P 500 index.

GM CEO Mary Barra expressed optimism about driving the NACS to become the unified standard for North America, encouraging greater sales of electric vehicles. Shares of both GM and Ford closed up over 1 percent following the announcement.

This partnership puts pressure on other companies to upgrade their charging networks to work with Tesla's infrastructure. Blink Charging welcomed the opportunity to collaborate with Tesla on interoperability with cables and connections.

While Tesla's opening of its Supercharger network brings advantages, there is a risk of overwhelming the stations and disappointing Tesla owners, or losing the competitive advantage of exclusive access to the best network.

Overall, this collaboration has positioned Tesla's charging network as a significant player in the industry, while presenting challenges and opportunities for other companies in the EV charging market.