If the market thinks the company won't be able to make a lot of profit, or the market thinks the company is approaching insolvency, the share price will tank.
In other words, falling share price is not a cause of insolvency, it can be an indicator for it. The share price quite literally is the market value of the company.
Of course it does. If a stock goes to $0, the company is essentially insolvent. Sure there are details of timing -- insolvency isn't exactly the same as bankruptcy isn't exactly the same as a stock price of $0 -- but in practice they all tend to go together and the company as a going concern owned by present investors is effed.
Splitting hairs over these technicalities is important for lawyers and analysts and management and in bankruptcy court, but not terribly important in the larger view. In the larger view, market cap via share price is a very practical reflection of the overall health/viability of a publicly traded company.
But it’s also not splitting hairs. It’s important to realize that equity price has no bearing on the company itself. You’re talking about something different than what was being discussed. You’re saying share price is correlated to expectation of company performance. What was being discussed was company performance is related to share price. One direction is true but the other isn’t. Companies see their valuations fall for all sorts of reasons that are not reflected in actual performance. Thats often because of a hype cycle that deflates, or maybe a scandal involving an executive, or whatever. This fall in valuation doesn’t impair the company in the least, except for if they need to raise capital by issuing equity.
May companies get delisted, which effectively brings their share price to the penny stock levels. They sometimes resurface and relist. Companies also can do certain corporate actions that make their stock basically worthless. The key is that while a stocks price sometimes corresponds to actual performance, actual performance is never impacted by stock price.