The neutrality act of 1939 allowed nations at war to buy supplies as long as
a. did not attack the united states
b. used the supplies for peaceful purposes
c. paid cash and moved the supplies themselves

first paragraph (and busy all the night ,with a silence deep and white )

the answer is: must pay taxes on profits

since it is considered as a part of your income, profits from investments is eligible for tax payment.

the tax from your investment could be influenced by how long you decided to sell it. united states promotes keeping your investment for long term period. so, the tax rate for investments that you sell in less than one year is typically higher compared to investments that you sell in more than one year period.