A landmark agreement has allayed investors' fears about QuantumScape's prospects.Don't let that headline confuse you: QuantumScape (QS -2.19%) stock's wild ride this year is a story worth diving into.Shares of the electric vehicle (EV) battery start-up kicked off 2024 on a somber note and lost 29.2% of their value in the first half of 2024, according to data provided by S&P Global Market Intelligence. A dramatic rebound in July, however, means QuantumScape stock is now up nearly 27% year to date, as of this ...