U.S. and Chinese tech giants’ stock have been on an upward path — until this year.

Since June, there has been a nearly 50% performance gap between China and U.S. internet stocks. While FANG (Facebook, Amazon, Netflix and Alphabet’s Google) stocks are sending the S&P 500 to record highs in its longest bull market, Chinese internet stocks are down along with the Chinese domestic equity market and its currency, the yuan.

Since the beginning of this year, billions of dollars of market value have been wiped out from China’s largest tech giants — Baidu, Alibaba and Tencent, known as BAT. Shares of Tencent (TCEHY), China’s largest social media and gaming company, plunged almost 30% from its peak in January, after an eye-popping 114% rise in 2017. Alibaba stock (BABA) has pulled back 20% from its June peak, and bounced back a bit after Thursday’s earnings report.

So far, the Invesco PowerShares NASDAQ ETF (QQQ), an exchange-traded fund based on the Nasdaq-100 Index with major holdings in Apple (AAPL), Amazon, Microsoft, Alphabet and Facebook, has had a strong year with 14.2% growth. The Invesco China Technology ETF (CQQQ), which holds big tech names in China, including BAT, however, recorded a 20.7% drop.

The massive performance divergence is a reflection of investors’ concerns over a slow down in the Chinese economy, which has dragged down the emerging market index across the board. Since the trade dispute between Washington and Beijing escalated in February, the Shanghai Composite Index has dropped by 17.3%, and the yuan has fallen sharply against the dollar, once trading close to a rare level of 7.

The trade war and U.S. government’s increased scrutiny on direct tech investments from China have contributed to the selloff, according to Jun Bei Liu, portfolio manager of Sydney-based Tribeca Investment Partners.

FANG stocks have benefited from their Chinese counterparts’ volatile run. This year, stock investors reduced emerging market and Europe exposure and added U.S. equities to their portfolios, which they see as safer destinations to park money. The moves are creating a shortage of U.S. stocks.

“As the Fed is creating a shortage of U.S. dollars, and Trump’s trade wars and sanctions are further boosting the USD, the U.S. stock market attracts more investors,” JPMorgan analysts wrote in a note on Wednesday. Since April, $100 billion has been added in equity exposure, mainly in U.S. equity indices.

“Tech sector [in China] had previously been the large beneficiary of such large inflow, now it is seeing the reverse,” Liu told Yahoo Finance in an email.