Yes, the same as anything else that's for sale. Supply and demand.Wossname wrote:I believe that share prices can rise as demand for them increases (though something called “market sentiment” is key and demand can reflect this).
One of my previous jobs was writing software for streaming stock market data to an investment application (called Sharescope). As background for that job (and out of curiosity) I learnt a bit about the mathematics of financial derivatives. It's a large and interesting subject in its own right. But, yes, people design algorithms for calculating when to buy and sell stocks, FX, commodities and a whole host of financial "products" that are derived from those things. Those people are called "Quants". It's a massive industry. Have a look at a jobs website (e.g. JobServe) and search for jobs with "Quant" in the title.I am no expert on the stock market but Max Keiser (RT channel) claims that some institutions and some wealthy individuals sometimes use computer algorithms to buy and sell (he claims to have written such if I recall correctly).
Yes, generally speaking, when people trade stocks, the motive is to make money. The question is: when does that activity help the business by allocating money to where it can most efficiently be used? And when does it cause harm? That appears to be a subject of debate. For example, there is debate as to whether "short selling" (essentially, betting that the price of a stock will fall) is helpful or harmful for the process that stock markets were designed for: allocating money to where it can most efficiently be used.The motive is not so much to support a business, but just to make money. If you buy enough, or sell enough, I believe you can affect the price either way and make money either way too.
Since you mentioned motive: As a general principle, if the motive is to make money, would you automatically regard that as a bad thing? Suppose I spot that a company is well managed and therefore has the potential to grow. Suppose I then decide to invest in that company on the expectation that the company will grow and that my investment will grow with it. Suppose my investment allows that to happen, and the company thereby grows and employs more people. Isn't that a good thing?