Tesla Inc. led the S&P 500 Consumer Discretionary index and was the third-best performer in the S&P 500 in December 2020 following its debut on the benchmark index.

Consumer discretionary stocks rose 2.5% during the month, underperforming the S&P 500's 3.8% growth, according to data compiled by S&P Global Market Intelligence. All 11 sectors of the wider S&P 500 index grew for the second consecutive month in December.

Shares of Tesla, the largest company ever to join the S&P 500, increased 24.3% in December. The electric-car maker's stock jumped nearly 6% on Dec. 18, 2020, the last day of trading before its debut on the S&P 500 on Dec. 21, 2020.

Ralph Lauren Corp. was also among the 10 best performers in the overall S&P 500 index during the month as it registered a 21% share price return.

Shares of Ralph Lauren rose 3% on Dec. 10, 2020, after Citigroup upgraded the fashion retailer to buy from neutral, stating that it is "making the right moves to upscale the brand" and cut expenses, according to Barron's. Goldman Sachs also upgraded Ralph Lauren by two notches to buy from sell, a separate Barron's report noted.

PVH Corp. recorded a share price growth of 18.1% during the month and was the third-best performing consumer discretionary stock. The apparel retailer's shares rose 3.8% on Dec. 4, 2020, after reporting earnings for the third quarter of fiscal 2020 that beat analysts' expectations.

Off-price retailer Ross Stores Inc. posted a 14.2% share-price increase in December, while casino operator Wynn Resorts Ltd. registered a 12.3% return.

Three consumer discretionary companies were among the 10 worst performers in the overall S&P 500 index in December.

Best Buy Co. Inc.'s shares fell 7.8% during the month, making it the worst-performing consumer discretionary stock. The electronics retailer was also among the bottom performers in the sector in November 2020.

Shares of Best Buy dropped 2.4% on Dec. 11, 2020, after Goldman Sachs downgraded the company to sell from neutral. The bank said it was downgrading the stock due to valuation concerns and potentially difficult comps, among other reasons, CNBC reported.

Whirlpool Corp.'s stock declined 7.3% during the month. On Dec. 23, 2020, Zacks Investment Research downgraded the household appliances manufacturer to neutral from outperform, citing the negative impact of sales declines in North America and Asia on its performance.

Homebuilder D.R. Horton Inc. posted a 7.2% decrease in December.