It's a quarterly rebalance of the entire S&P ASX index. Some stocks , for various reasons, get included and some stocks are ejected ..........which occurs after EOD on the 18/03/16.
It should under pin the BWX share price, as various investing entities, as part of their remit, can only invest in stocks which are in the S&P index(es).
BWX Price at posting:
$4.27 Sentiment: Hold Disclosure: Held