China's securities regulators announced Saturday that Hong Kong, Taiwan and Macao residents who live on the mainland will soon be allowed to open A-share accounts.

In recent months, the China Securities Regulatory Commission (CSRC) has put forward several such measures to bring more capital into A-share markets while also keeping supplies in check by getting stricter with initial public offering applications.

Stock markets have recovered somewhat due to these policies, but the good times can't last forever.

The A-share markets still lack rules to discourage speculation. Though regulators released new listing and delisting rules in 2012, they have yet to prove effective. It is still common to see speculators inflate junk share prices. In an unhealthy and immature stock market, bringing in capital only produces false prosperity at best and dangerous investment bubbles at worst.

The author is Yang Guoying, an economic commentator.