HONG KONG, May 23 (Reuters) - Hong Kong shares dropped to the lowest since January on Wednesday, tracking broader weakness across Asian markets as investors fretted over the growing risk that Greece could be on its way of the euro zone.

A tepid rally in the previous session gave way to a decline in Hong Kong, where the benchmark Hang Seng Index fell 1.33 percent. It is now up just 1.9 percent this year as the 10.9 percent drop so far in May threatens to wipe out gains for 2012.

In mainland China, the Shanghai Composite Index closed down 0.42 percent and the large-cap CSI300 eased 0.41 percent.

HIGHLIGHTS:

* Corporate governance issues were a concern for a second-straight session. Shanghai Pharmaceuticals Holding Co Ltd lost a quarter of its value to hit a lifetime low after Chinese media reported that an asset recently acquired by the company was under investigation by securities regulators.

* The technology sector also struggled after a weak second-quarter outlook from Dell Inc and a further tumble in Facebook Inc shares. Chinese internet giant Tencent Holdings Ltd remained on the backfoot, losing 0.3 percent. It is now down more than 14 percent in May after jumping almost 13 percent in April. Lenovo Group Ltd, the world's No.2 PC maker by sales, slipped 1.5 percent but recovered off of lows after posting results that were in line with expectations. (Reporting by Vikram Subhedar and Clement Tan; Editing by Chris Lewis)