All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
It is forbidden to farm pigs, trade in them or benefit from them in any form because they are filthy in themselves. The evidence on this is that Jabir bin `Abdullah narrated: I heard Allah's Messenger (PBUH), in the year of the Conquest of Mecca, saying: "Allah and His Apostle made illegal the trade of alcohol, dead animals, pigs and idols." {Agreed upon}. Idols, here, refers to shapes of living creatures.
As for trading in gold, it is permissible so long as the conditions of Sharia, in this regard, are met. Thus, it is permissible to sell gold for gold under the condition that they are of equal weight, payment is made on the spot and in the same sitting.
It is also permissible to sell gold for silver provided that payment is made on the spot and in the same sitting. It is also permissible to sell gold for silver of unequal weight because the two items aren`t from the same kind. However, it is forbidden for men to wear gold, but it isn`t forbidden for them to trade in it. And Allah The Almighty Knows Best.
