How can I estimate the disconnect between book value and market capitalisation? There are several questions on Stack Exchange as to what difference the stock price makes to a company after its IPO. Surely, management cares, it is important to be credible to trading partners, etc.

However, with passive investment being about 50%(?) of the stock market and at the same time the stock price not having a direct influence on the balance sheet, external shocks like the coronavirus won't be blamed on management. To some extent the stock price is just determined by people talking up (sellers) or down (buyers) the stock price. Perhaps short sellers talking it down and long holders talking it up.

How do I make a quantitative indicator that describes the disconnect between the market capitalisation and the book value? What options are there?

Sub 1: When it is said there is an asset price bubble, it usually means stock prices (or RE). Are the assets that actually are on companies' balance sheets also inflated?

I thought it interesting to be an investor: to invest in companies that have worthwhile plans. In reality however, I seem to be buying stock (secondary market) from previous stockholders (primary market). The problem is that the primary market largely ceases to exist after the IPO. You might say that stock buybacks and re-emissions are primary market operations, so I guess my question is focused on the difference between those two.

Sub 2: Why are secondary market participants called investors?

Sub 3: Would it be possible to keep the primary market alive by changing the law?
The context of the question is analysis of the plans of the company, the market price, and the book value.
Primary investors provide cash or other resources to the company in exchange for original debt or equity claims against the assets of the company. The company is expected to purchase assets with the cash as it executes the business plan. Secondary investors purchase the debt or equity claims from a primary investor so the company does not get any cash from these secondary transactions. The question is how to estimate the disconnect between market capitalization and book value.
Understanding Price-to-Book Ratio:
https://www.thebalance.com/fundamental-analysis-understanding-price-to-book-ratio-3140794
The calculation of book value:

(Assets - Liabilities)


Ongoing, financially-sound companies will always trade for more than their book value because investors price the stock based, in part, on their anticipation of the firm's future growth.

The Affordable Growth Rate (AGR) is a formula appearing in the book 101 Business Ratios by Sheldon Gates. According to Gates the formula was used by Hewlett Packard. This article describes AGR

https://www.inc.com/magazine/19861201/9293.html


The AGR is a growth strategy based on two assumptions. The first is that your sales can grow only as fast as your assets. If yours is like most firms, for example, you can't increase your sales by 30% unless you increase your receivables, your inventories, and your fixed assets by about 30% as well. The second assumption is that your firm has a target debt-to-equity ratio and that your lenders are willing to continue to extend credit at that ratio. This assumption implies that as your equity grows, debt can grow at the same rate, allowing you to maintain a constant debt-to-equity ratio.

The sources of cash to grow assets, and therefore sustain sales growth, is debt, equity, and retained earnings. When a firm is taking venture risk the future cash flows in the form of retained earnings are not expected to be sufficient to cover the growth of assets in support of sales growth. When a firm is throwing off cash it has high retained earnings or profit that can also be used to pay dividends. There is another book called The Cash Flow Problem Solver, by Bryan E. Milling, which describes in detail how a company can grow too fast and cause a cash flow crisis that results in bankruptcy.
There is no direct link between market capitalization and book value because market capitalization is the last sale of one or more shares of stock in a secondary market transaction based on the desire of the buyer to own shares at that price and the seller to own cash rather than shares at that price. The market capitalization contains a liquidity premium if the shares are relatively easy to buy and sell on the secondary market and a growth or discount factor, based on expected future events, so there is a disconnect between market capitalization and book value.
If the firm is expected to remain a going concern and grow assets, sales, and profits in the future, especially after reaching cash flow break-even following new injections of debt or equity, and if it can grow from internal finance of retained earnings from operations after getting past cash flow break-even, then there is a premium in the share price above book value. There is no particular formula for evaluating the plans, asset position, debt and equity claims of a company, and there is no particular formula to forecast future sales, profits, and retained earnings, and there is no particular way to put a premium or discount factor on the share position, so there is no particular way to link market capitalization to book value.