Do I need to pay estimated taxes quarterly if I make enough trading stocks?

I have a full time job and have started trading stocks few months back. Already I have enough realized gains that will force me to pay additional tax. My question is do I need to pay estimated taxes quarterly based on the profits I have made so far or can I wait till the end of the year to pay my taxes.
Any one who has been in this situation, if you can share your experience, it will be greatly appreciated.

Which broking house is offering to buy online Mutual fund as i would like to do trading & Investing ?

Which broking house is offering to buy online Mutual fund as i would like to do trading & Investing ?
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