What is an ETF?
An exchange traded fund holds a basket of stocks, bonds or commodities and trades on the stock exchange like a single share. Most track an index such as the S&P 500, so their price follows that index.
Which S&P 500 ETF should I pick?
SPY, IVV, VOO and SPLG all track the S&P 500 and move almost identically. They differ mainly in yearly cost and in how much they trade each day.
What are leveraged ETFs?
Funds like TQQQ aim for 3 times an index's move each day. Because they reset daily, holding them for weeks can give results far from 3 times the index, especially in choppy markets.