I am in general agreement that Fundamental analysis is generally useless in buying or selling in the market.

On the other hand I believe it does have an important role to play in the sale of a complete company which potential takeover parties consider and the Board of directors considers in deciding to take such an offer as being good for the owners (Shareholders) of the company and put it up for approval with a recommendation.

In such a case the possible purchasor figures out what the whole business is worth to them and then considers whar a competitor would consider it worth and how much is keeping the possible competitor out worth.

The board of directors figures out what the business is worth  in consideration of a number of factors such as the various difficulties of bring the product to market and future profits to be made from it and a whole lot of other factors.

Other than that the individual shareholders must look at their own vision of the future and the current trading price and possibilities of dividends and a whole load of personal factors when deciding to either sell at the current price at which the shares are trading.

Individual shareholders can then either sell some or all or buy some more or invest incomimg dividends wherever they feel is best.

there is no magical formula but there are a very large number of ways of looking at any investment.