In a more popular understanding, we are talking about misinformation. The main priority that regulators have when it comes to protecting the market in securities and commodities is that the markets are "fair" and that everybody has equal access to information. A market with the so-called "perfect information", which guarantees that everybody has access to complete information, creates a perfect allocation of capital to the best companies that will produce the higher return on that capital, therefore maximizing the overall economic growth. For example, suppose investors believe that Apple can create more economic value than Alphabet. In that case, Apple is priced higher on the market, which allows it to attract more capital at better terms.
Of course, there is no perfect information in reality, and any person is not realistically able to aggregate and process all the information. This is why there's a need for a fair market, which works like a collective brain of the society, aggregating knowledge and skills from multiple individuals and entities. At least until market manipulation comes into play.
Market manipulation happens when somebody distorts the market information. For example, a trader or even the issuer may create fake volumes to make the asset seem liquid. In reality, this can easily turn out to be a pump-and-dump scheme, in which case the price is artificially increased only so that beneficiaries of the scheme could sell the large volumes of an asset, bringing the price back down.