Anecdotally - because I haven't looked for any hard data to back...

Anecdotally - because I haven't looked for any hard data to back this up - but I think the inability of IMM to hold its gains comes in part from the US stock. The sentiment there is invariably negative when you look at the retail trading forums, with some holders having seemingly unrealistic expectations of short term gains, others who are just in it to profit off the churn and are actually keen to see it swing with greater volatility, and a market that maybe doesn't fully understand the business or its pipeline/position as well as the Aus market does. If true, then perhaps the company is just not articulating itself well enough to US investors, or that US retail investors are getting so Gamestopped these days that examining the underlying fundamentals is simply not important to them. I think this has a bearing on the way the company is viewed overall, and that sentiment flows through to the ASX stock.