Beta: your share of a basket
Your share of a validator's basket is counted in beta.
Beta is not a new coin. It is not TAO and it is not alpha. It is a count of shares in one basket. If a basket has 100 beta in total and you hold 40, you own 40% of everything in it.
Your beta count stays the same when prices move. It goes up when you earn more shares and goes down when you claim. What changes with the market is what each beta is worth in TAO.
Every validator's basket is separate, so beta from two validators cannot be added together, just as you cannot add shares in two different companies. To compare them, look at their value in TAO.