I don't think it's a bug, hence why I'm placing this under suggestions, but it might be. I have a feeling it's just an odd quirk of how the game does its accounting.
It is related to an exploit. Essentially, you produce a cheap item (like CPU), and sell it to yourself (doesn't even have to be a subsidiary) at the highest price, then store it in a warehouse. The game, incorrectly, considers the inflated value to be "profit" and your share will skyrocket, allowing you to issue billions in shares over just a year (depending on your patience).
I don't really care about the exploit - after all, I can just not do it.
However, it does reveal the accounting quirk and I suggest that the game should track it differently. I might have misunderstood the quirk, but here's what I think is happening:
When I produce a good, the game undervalues the asset - so my stock price is lower than it should be at that point in time.
If I then sell the good to a competitor, there's no issue - I lose the asset and get cash.
But when I sell the good to myself, the game suddenly doublecounts the good: I lose an undervalued asset, I sell it at X price, I buy it at X, and I gain an asset at X price, thus a net profit (which I will lose if the good is cleared or sold at less than X - so it does resolve itself eventually).
The problem, outside of the exploit, is that the game is obviously doing this for every other internal transaction in the game as well. Therefore, the share price of my company is always inaccurate, potentially by quite a bit. And frankly it shouldn't be, because even if my assets are growing, my profit in the above scenario (where I sell a good to myself) should always be 0. The game can believe i have a high revenue, sure, but it currently thinks I have a high profit, and that's obviously incorrect.