Stories like this or this always leave a bad taste, however much those involved protest their innocence.
That's another advantage of deposit-funded corporations, which wouldn't have shares which can be bought and sold on the stock exchange. They'd be like building societies (or LLPs, partnerships or unit trusts), you make your deposit, you are allocated your share of profits or losses each year (or month or quarter) and you withdraw your deposit plus accumulated profits when you need the money, or you would rather deposit with a different company which you think will give you a better return.
The point about insider trading is that you buy if you expect good news, i.e. the announcement of future profits, and you sell as soon as the news becomes official or public knowledge and the price has jumped. "Buy on a rumour, sell on a fact".
With DFC's, there'd be no point cashing in if future profits are expected to be higher, you'd sit tight and hope for a share of it. OK, you would still have an advantage if you knew the rumours before everyone else because you could add to your deposit before the news become official or public knowledge. But you wouldn't get your share of those profits until they are actually made and it would leave a longer paper trail.
Similarly, if you have insider knowledge of potential bad news (like the insurance company finding a loop hole that means they don't have to pay out on a factory which burned down), you would be tempted to cash in. But the company would have to make a provision for the future losses as soon as it knows and knock a percentage off everybody's deposit. So if senior managers withdrew their deposits before they make the provision and announce the bad news, that would be straightforward false accounting and fraud and much easier to prove than 'insider trading'.
And there would be no incentive to spread false negative rumours (to give you a buying opportunity) and then refute them (to give you a sell opportunity). Or vice versa. The amount of your deposit is entirely unaffected by rumours either way, the amount you can withdraw is only affected by what has actually happened in the past.