Facebook Inc is on the preliminary list to join the Russell 3000 index, according to Russell Investments on Monday.

Facebook will be the largest addition to the index in market capitalization. The social network giant made a market debut in May. Among other IPO additions to the Russell 3000 are software maker Splunk Inc and financial services provider EverBank Financial Corp.

Apple, with market capitalization of $540.2 billion, is expected to replace ExxonMobil with $367.7 billion market cap, as the largest company in the Russell 3000, Russell Investments said. Apple grew its market capitalization by 68 percent in the last year.

The combined capitalization of stocks in the Russell 3000, which reflects about 98 percent of the investable U.S. equity universe, will decrease from $16.7 trillion at May 31, 2011 to $15.8 trillion as of May 31, 2012. Similarly, the median market capitalization will decrease from $1.04 billion to $910 million.

"Russell's index reconstitution reflects the market decline over the past year. That said, returns have been far from uniform," said Steve Wood, chief market strategist for North America at Russell Investments.

"Even as the flare-up in the euro zone crisis, China's slowdown and relatively soft U.S. economic data have weighed on investor sentiment in recent weeks, the global markets showed resilience when viewed over the course of a year. Furthermore, Russell Indexes reflected diverse returns and decreased correlations across global markets in the last year, reinforcing the importance of a well-diversified global multi-asset portfolio approach."