Simple tax question

Quick tax question :
Lets say I buy a stock whose value is $100.
A month later , I sold the stock for $200 and cashed out the money

Net short term gain is $100.

Now after few months( in the same year), I see that stock price is $100 again and I bought 2 shares of the same stock there by reinvesting the entire amount,

Do i still have to pay tax as short term gain for $100 eventhough i reinvested ?

#investments #personalfinance