Some market observers believe the Shanghai-Hong Kong Stock Connect is partly responsible for $11 billion in net outflows from China equity exchange-traded funds since September.

A-share ETFs were previously the only way for foreign investors to gain access to onshore Chinese stocks if they did not have offshore renminbi quotas, but that is no longer the case. The November launch of Stock Connect allows direct trading of shares on the Shanghai Stock Exchange via Hong Kong's bourse and vice versa.

Despite the mainland's benchmark CSI 300 index gaining 54% between the end of August and January 15, ETFs tracking it have seen withdrawals every month since September, according to data and index provider Markit.

A-share ETFs posted four consecutive months of net redemptions from September to December of $1.3 billion, 2.9 billion, $2.3 billion and $2.4 billion. And the first 15 days of January saw net withdrawals of $2 billion.

The fact that the outflows have been largely out of Hong Kong-listed ETFs may support the idea that the Stock Connect trading link is a factor, noted Simon Colvin, an analyst at Markit.

Between them, the iShares FTSE A50 ETF (a non-RQFII A-Share product) and Hong Kong-listed RQFII ETFs recorded a net outflow of Rmb46.9 billion ($7.5 billion) in the last quarter of 2014, said Jackie Choy, an ETF strategist at investment research firm Morningstar.

The A-share ETF outflows do not exactly match cross-border northbound trading flows, said Choy, but they were big enough to support the theory that Stock Connect is luring some of the money.

However, another reason cited for the ETF outflows has been arbitragers booking profits.

Arbitrage investors had bought Hong Kong-listed China ETFs in the hope of exploiting discounts in A-share prices compared to their H-share counterparts, said Susan Chan, Asia-Pacific head of BlackRock's iShares ETF unit. But these trades reversed in December after Stock Connect’s launch in November, as investors booked profits.

Stock Connect has seen the total value of northbound trades (those through Hong Kong into mainland stocks) hit Rmb90 billion, or 30% of the aggregate quota as of Friday.