Some merchants are bugged - they have the dialogue allowing you to pay them 500 gold, but doing so does not result in any permanent change in the merchant's available gold. The perk allows you to invest 500 gold in certain merchants, after which that merchant will permanently have 500 more gold available. The merchants who have more gold are all identified in the notes of the following tables. The perk increases nearly all merchants' gold by 1000. Merchant gold can be increased in several ways. Gold is reset each time the merchant's inventory is reset or every 48 hours. Merchants will generally have 3-40 gold more than listed, because their personal pocket change is added to the merchant-specific gold. Thoughtful investment selections that meet your goals and risk profile keep individual stock and bond risks at an acceptable level. There are some risks you have some control over and others that you can only guard against.
For those added by the add-on, see.The amount listed under 'Gold' is the base amount of gold that the merchant has available to purchase items from the player. A merchantThis page summarizes all of the merchants available in Skyrim.