I think market cap is one of the criteria for admission into the S&P/ASX20, or S&P/ASX200 or S&P/ASX300. Other requirements are liquidity, ASX listed etc..
Institutions do balance their portfolios when shares are included in/excluded from the indices.
Whilst $100m may not be the magic number or the threshold to trigger institutions buying, I am quite confident that BIG will be on their radars if its market cap goes north with the prospect of index inclusion.
BIG Price at posting:
66.0¢ Sentiment: Hold Disclosure: Held