Southwest Airlines Co. (NYSE: LUV) is North America’s third-largest airline. The airline is known for discount fares and having the world’s largest fleet of Boeing 737 aircrafts. Southwest released its Q3 2018 earnings on October 25, 2018. The company reported revenues of $5.58 billion, compared to $5.27 billion over the same quarter last year. As of October 25, 2018, Southwest's market cap is $28.28 billion.

Here are the five largest mutual fund investors backing Southwest Airlines, who collectively own 13.42% of outstanding shares. 

Vanguard PrimeCap Fund (VPMCX)

The Vanguard PRIMECAP Inv (VPMCX) is an actively managed large- and mid-cap stock fund. The fund’s objective is the long-term appreciation of capital. The fund’s benchmark is the Standard & Poor’s 500 Index (S&P 500 Index), and it outperforms the index significantly. VPMCX owns 35 million shares of Southwest Airlines, roughly 6.12% of the total company. The Vanguard PrimeCap Fund has $69.5 billion in total assets, with its investments in Southwest accounting for 2.79% of the fund's portfolio.

Vanguard Total Stock Market Index Fund (VTSMX)

The Vanguard Total Stock Market Index Fund (VTSMX) is a passively managed stock index fund. It seeks to match the overall return of the entire U.S. stock market. Portfolio managers invest in more than 3,700 stocks, according to each stock’s weighting in the CRSP U.S. Total Market Index. This index covers almost the entire capitalization of all stocks traded on the New York Stock Exchange (NYSE) and the NASDAQ. The fund does a near-perfect job of matching the index. The fund owns 13 million shares of Southwest as of October 25, 2018, 2.29% of the airline company's total shares. The Vanguard Total Stock Market Index Fund's stake in Southwest represents 0.11% of the fund's $756.6 billion portfolio.

Vanguard Capital Opportunity Fund (VHCOX) 

The Vanguard Capital Opportunity Inv (VHCOX) is an actively managed stock fund. The fund’s goal is the long-term growth of principal. Its benchmark is the Russell Mid-Cap Growth Index, even though the average capitalization of the fund’s portfolio is three times the average capitalization of companies included in the index. It significantly outperforms the index. With 10 million shares of Southwest, or 1.76% of the company, VHCOX is the compay's third-largest mutual fund holder. The fund's total assets are valued at $18.4 billion and the fund's investments in Southwest represent 3% of its portfolio.

Vanguard 500 Index Investor (VFINX)

The Vanguard 500 Index INMV (VFINX) tracks the S&P index and attempts to replicate it as closely as possible. The fund manages 509 stocks, with 14.28% of their assets going to their top 5 companies, which include heavy hitters like Apple, Microsoft, and Amazon. The fund is managed by Donald Butler, who took over for Michael H. Buek in 2016. VFINX's 9.6 million stocks of Southwest represent just 0.1% of the fund's $459.3 billion portfolio.

Vanguard PrimeCap Core Fund (VPCCX)

The Vanguard PrimeCap Core Fund (VPCCX), similar to its sibling the PrimeCap Fund, is managed with a long-term perspective, extremely low turnover, and a well-established investment strategy. Unlike the PrimeCap Fund, however, which focuses on growth-oriented stocks, the PrimeCap Core Fund invests in stocks with both value and growth characteristics. The mutual fund has invested 4.28% of its total portfolio in Southwest and holds roughly 9 million stocks, about 1.57% of the company. VPCCX holds $11.7 billion in total assets as of October 2018.