One metric I find useful when assessing the operating performance of a company is ROIC or return on invested capital. I calculate it by taking operating profit as the numerator and dividing by equity plus debt less cash less owned stocks. If you want to isolate the performance of the core business, this is a pretty good metric. One might even further subtract the value of land (without buildings on it), but I don't think the game lets you break that out. It would be great to see that metric over time in a graph or something.
One could perform the same calculation excluding debt from the denominator and subtracting interest expense from the numerator to calculate a core return on equity.
Also, since I use this metric, I find the game's way of accounting for acquisitions somewhat frustrating. If you purchase another company for above book value, the premium to book is immediately deducted from net income and removed from the balance sheet. In the real world, assets of an acquired company are recorded at fair value on the acquirer's balance sheet and any premium to the fair market value is recorded as goodwill, which is periodically tested for impairment.
It would be impossible to implement this in the game, but any premium to the book value of acquired assets could be allocated to goodwill. Until fairly recently, US GAAP required companies to amortize goodwill. I think in the game goodwill could be amortized over a period of say 10 years (a reasonable period of time for the franchise value of a given business to decay without further investment in advertising, R&D, etc.). Since there is no way to test for impairment, I think this is better than leaving it on balance sheet indefinitely, which would inflate a company's assets, perhaps improperly.
I'm also curious about some other game data. I'd like to know under different conditions what the long run return on investing in AI stocks and the long run average real interest rate look like. It can be difficult to come up with my required expected return on various investments vis a vis the opportunity cost of investing in stocks. This is especially difficult when all the good AI stocks are bought up. At that point, since my return on cash is deeply negative after inflation, I wind up buying anything and everything rather than letting my cash be inflated away. If there were a risk free asset like treasuries to buy, that would be a good minimum return. If there were more stocks available, weighted average cost of capital would be a helpful concept too.