Roku (ROKU) had the highest return between 2018 and 2021 by a large-cap US stock in the Communication Services Sector, returning 333.5%.

ASSET	YEARS	% RETURN
Roku (ROKU)	2018-2021	333.51%
Netflix (NFLX)	2018-2021	207.21%
Live Nation Entertainment (LYV)	2018-2021	180.11%
Alphabet Inc Class C (GOOG)	2018-2021	176.02%
Alphabet Inc Class A (GOOGL)	2018-2021	175.12%
New York Times (NYT)	2018-2021	166.35%
Charter Communications (CHTR)	2018-2021	92.65%
Pinterest (PINS)	2018-2021	91.32%
Facebook (META)	2018-2021	89.3%
Liberty Media Corporation Series C Liberty Formula One Common Stock (FWONK)	2018-2021	83.62%
T-Mobile US (TMUS)	2018-2021	81.5%
Liberty Media Corporation Series A Liberty Formula One Common Stock (FWONA)	2018-2021	80.04%
TKO (TKO)	2018-2021	66.05%
Warner Music (WMG)	2018-2021	63.57%
Take-Two Interactive Software (TTWO)	2018-2021	61.52%
Roblox (RBLX)	2018-2021	59.94%
NetEase (NTES)	2018-2021	55.13%
Telus (TU)	2018-2021	49.31%
Walt Disney (DIS)	2018-2021	46.19%
News Corp (NWSA)	2018-2021	44.4%
News Corp (NWS)	2018-2021	42.48%
Spotify Technology (SPOT)	2018-2021	41.07%
Chunghwa Telecom (CHT)	2018-2021	38.62%
BCE (BCE)	2018-2021	35.1%
America Movil SAB de CV ADR (AMX)	2018-2021	33.98%

Large-cap stocks are treated as having a market cap of $10B+.