<prompt> Human: Hi,Im new to investing. I started a Roth IRA this year and fully funded with 5,500. I put it all in a target date mutual fund Vanguard 2050. Everything I read says you are supposed to buy then just sit on those mutual funds. My question is if I can accurately predict when it will go up and down is there any downside to selling it when its high then re-buying when its low inside the ROTH IRA vehicle. I couldnt find a clear answer googling. I havent gone through a tax season with this thing yet so I dont know if theres a tax disadvantage to this but it is my limited understanding that taxes on gains dont apply within a Roth IRA.Thank youEdit: Seems to be a consensus ranging from polite and helpful to condescending that this should not be attempted, and thats cool. Thank you very much for your advice. I was however more interested in the mechanics of how such a thing would work inside of a Roth IRA and if there would be some kind of transaction limit or hidden cost if this were able to be done. Special thanks to tu_che_le_vanita for answering that.  <response>: If thousands of data scientists and analysts with billions of dollars of technology cant predict the market on a consistent basis, you cant. Continue to add 5,500 annually to your Roth and enjoy your savings when you get old. 