I suggest starting the the historical company announcements and...

I suggest starting the the historical company announcements and reading the full threads back 12-months if you want to read the respective opinions. My take on the history is/was:

1. Previous AGL management was looking at low-cost renewables to reduce future costs but was still comparably committed to getting the most out of their coal assets.
2. They were getting slammed on profitability of some of these legacy assets (partly industry dynamic, partly unprofitable legacy contracts, but also due to maintenance and reliability) and the AGL share price tanked to $5ish.
3. To deal with this they were looking at splitting the old and new businesses. A cynical person might say this might also help them quarantine their liabilities into the "legacy" entity (and potentially push any remediation onto the taxpayer) as well as generate windfall profits for their merchant bank advisors.

MCB publicly opposed this, took an interest in AGL through his investment vehicle, initiated some board changes and the split has been scuppered along with a more aggressive timeline for transition to renewables. Since that time the share price has recovered, I'd suggest due to a combination of factors (improved industry pricing is a big factor but AGL's own policy has contributed to the short term price recovery, continuation of coal would have trashed new investment in renewables. A clear board strategy and removal of the split option has also helped imho).

The salty anti-MCB brigade on here seem to regard the split as the preferred outcome even though it basically would have ended the last sizeable Australian industry player (despite their names, the other larger players are Chinese or HK owned so that's where your dollars go on your high power bills) and they almost certainly wouldn't have seen the recent AGL $12 share price in that scenario. Go figure why they're salty.

The culmination of all this was the recent FY24 guidance market update (suggest you look at that announcement) which led to the recent rally from $8 to $12. From here everyone can do their own calculations on likely FY24 per share profits, dividends and Franking based on that update.

I took some profits off the table on announcement day and would like to buy back in but it's not as compelling as at $8 and it's hard to buy back when your current holding price starts with a 7.

I have no opinion on the short term direction of the share price from here but I'm clearly in the camp that MCB has been good for AGL investors (it's when I started buying but that's all in the past). If you're asking what happened short term I'd say it's not at all surprising that a share that's rallied hard into an announcement comes off post announcement.

As always, do your own research.