As you probably know all too well, Bitcoin is based on a distributed ledger called the Blockchain, which means it is decentralized and transactions are not mediated by a middleman (a bank). There is no central authority and it is not regulated like physical money. This lead to market manipulations in the past which caused the change in its price. So, the short answer to your question is yes – among other factors that cause the volatility of cryptocurrencies’ price, market manipulations are possible too. These manipulations are obviously financially motivated.
Researchers showed that the first time Bitcoin price rose to the $1,000, it was probably a result of a market manipulation. Widely known practices are “pump and dump” and “spoofing” which change the supply and demand for Bitcoin instantly and create better conditions for manipulators to sell and buy cryptocurrencies. These are happening on unregulated exchanges and are not officially illegal or forbidden.
Pumping is a process where a large group of people buy a certain coin at the same time. This will cause the rise in the price. After pumping of the price, the same group of people sell coins they bought, dumping it back to the market, by which they earn the difference.
Spoofing is another process where traders basically manipulate the psychology of users. They create false optimism or pessimism in buying/selling coins. They have no intention of fulling transactions, they just pretend. This gets users to sell their coins cheaply or to buy coins high and creates ideal conditions for the manipulator to proceed to the second phase, which is actually buying and selling of coins.
There were several manipulation scandals in the history of Bitcoin. Exchanges were accused of “spoofing” and “pump and dump”. For example, in Japan, two bots were pretending to transact coins, never finishing transactions. This created the change in the market, causing users to buy and sell their coins. Exchange earned a lot of money charging transaction fees.
Even though market manipulations can change the supply and demand of Bitcoin and cause the price to change, have in mind that the supply and demand of Bitcoin is determined by many other factors such as media, government regulations and growing popularity of Bitcoin as a means of transaction.