It's a huge business in itself here in the US. Granted they work better in lower priced low market cap stocks but also on stocks like SIAF you usually see some real affect, even if it's just for the short term. Of course not every promo is equally successful and some even fail if the company dilutes too heavy into it but as far as SIAF's promo is concerned, it hasn't even started or is already over again IMO.
Look up some of these charts. TEWI, TUCN, ACGX, LCAR. These were some promos in the last few months on stocks I owned. Look at the intraday spike on the first promo day. You will see it on the chart.
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