Before iPhone7 launch, Apple CEO Tim Cook sold large amounts of his assets, (probably without telling the news). Are these transactions tied to personal information?
What about private traders?
In the United States, when key people in a company buy or sell shares there are reporting requirements.
The definition of key people includes people like the CEO, and large shareholders.
There are also rules that can lock out their ability to buy and sell shares during periods where their insider knowledge would give them an advantage.
These reporting rules are to level the playing field regarding news that will impact the stock price.
These rules are different than the reporting rules that the IRS has to be able to tax capital gains. These are also separate than the registration rules for the shares so that you get all the benefits of owning the stock (dividends, voting at the annual meeting, voting on a merger or acquisition).
The broker will probably submit records to the IRS, so there isn't anonymity at that level...