Observing the gyrations in the stock market, at some point today the NASDAQ was up 0.30%, and as I tried to verbalize this figure, I realized how unnatural it is to say "it is up zero point three percent." OK, it may not be that bad, but what about the Dow being up right now "0.11%". Do people in finances say "up point eleven percent"? Do they revert to fractions?
Sometime people refer to 'points', such as the Dow Jones Industrial Average being up 200 'points'. That means that the price of the index increased by 200.
However, this is not particularly precise because you need to know what the value of the index is in order to determine how large the movement is. If two traders are talking to each other, that is probably fine as both will know what the typical price of the index is. If you're dealing with a member of the public, it can be less clear.
As a result, people (e.g. the financial news media) end up using percentages or sometimes "tenths of a percent".