By Kane Wu and Summer Zhen

HONG KONG, June 6 (Reuters) - U.S.-based investment firm Artisan Partners is shutting down its Hong Kong office by the end of June, two sources with knowledge of the situation said.

The firm is disbanding the Hong Kong-based team after it decided to shut down its Greater China strategy partly due to concerns about escalating Sino-U.S. trade and geopolitical tensions that have made investments in the world's second-largest economy riskier, said one of the sources.

Artisan, which is headquartered in Milwaukee, Wisconsin, and managed $164.4 billion globally as of the end of April, did not immediately respond to Reuters' requests for comment.

The sources declined to be named as the information was not public. Reuters could not immediately ascertain how many people would be affected by the shutdown of the Hong Kong office.

The firm's China post-venture strategy, a fund that focuses on Chinese small- and mid-cap public and private companies, had $113 million of assets under management at the end of April, according to the firm's monthly update.

In the same update, Artisan said the China-focused portfolio was in the process of winding down, without giving details.

The firm's retreat from Hong Kong comes amid the U.S. government's tightened scrutiny of American investments in China and an ongoing trade war that has clouded the business outlook of many export-heavy companies from China.

The U.S. government restricts U.S. investments in certain sensitive technology sectors in China, such as semiconductors, artificial intelligence and quantum computing.

U.S. investors are also restricted from investing in companies that are on the U.S. sanctioned entity list that comprise a growing number of those from China.

U.S. onshore investors were not able to buy shares of Chinese battery giant CATL 300750.SZ in its $4.6 billion Hong Kong listing last month due to the structure of the deal, CATL's filings showed.

CATL was placed on a U.S. Defense Department list in January of Chinese companies it says work with China's military.

By March 2025, Artisan's China post-venture strategy posted a net loss of 10.4% since its inception in March 2021.

"The largest risks for investing in China will continue to be geopolitics and domestic policy overshoots," Tiffany Hsiao, the strategy's portfolio manager, said in a client letter on the firm's website in April.

Outside the U.S., Artisan also has offices in London, Dublin, Singapore, and Sydney, according to its website.

The move follows the exit or downsizing of several North American asset managers and international law firms from Hong Kong over the past few years.

Ontario Teachers' Pension Plan, Canada's third-largest pension fund, announced the closure of its Hong Kong office in March.

(Reporting by Kane Wu and Summer Zhen; Editing by Jamie Freed)

((kane.wu@thomsonreuters.com; +85228436590; Reuters Messaging: kane.wu.thomsonreuters.com@reuters.net))