Ann: Appendix 4C - quarterly-SBB.AX, page-63

There are plenty of plausible explanations for the trade. I'm not going to read into it too much but here are some suggestions:
1-If Xu needs cash personally he can sell the shares to a relative then buy them back on market later. If the price stays the same this would allow him to do so without paying any of the cash out to public shareholders.
2-If Xu wants to buyout the smaller holders it is in his best interest to spook weak kneed investors. He can sell the shares to a relative or third party and cause a drop in the price. Given that another director recently bought shares to encourage confidence in the stock, Xu may have saught retaliation. The price was just starting to recover. If the price drops 10%-20% as a result of the sale then Xu is in a materially better position when he buys back the company. If Xu needs money personally this is a better option than sharing any of the cash. The company still more or less belongs to him. It was a few years ago that he got his big dividends.
3-Xu could be bringing another partner online and be willing to sell them shares cheap to get them onboard. This could relate to the recent purchasing on market. We will have to wait for an announcement.

Personally I think that 2 is the most likely. There are coincidences of events which are
1- The other director buying, potentially as a show of confidence
2- The price starting to recover as people realised the cash is not fake
3- Xu sells some shares off market
4- The price retreats again

So hopefully we are looking at a bottom and we are finally going to get an offer for our shares. It will mean less headaches for everyone.