Billionaire investor Ray Dalio's firm Bridgewater Associated tumbled in the fourth quarter of 2017. The largest hedge fund in the world maintains a stock portfolio of more than $12 billion, according to recent 13F filings with the U.S. Securities and Exchange Commission (SEC). This is a sharp decline in the list value of the stocks making up the portfolio.

Dalio's portfolio is down 18.4% over the previous quarter, according to a report by Valuewalk. By comparison, the S&P 500 Index gained more than 6% over the same time period.

Dalio's stock holdings are concentrated in a relatively small number of positions, and most of the largest stakes are in ETFs. (See also: Ray Dalio breaks down his 'Holy Grail.')

Largest Holdings Include Vanguard, SPDR, IShares

The four largest holdings that Bridgewater carried into 2018 comprised about two-thirds of the fund's stock positions. The largest of these holdings is Vanguard Emerging Markets Equity Index (VWO). Bridgewater held $3.16 billion in VWO as of the end of 2017, a sum accounting for more than a quarter of the firm's total stock holdings.

The next largest position is in SPDR S&P 500 ETF (SPY). This position was more than $2.5 billion, accounting for nearly 21% of the firm's total portfolio.

Following this were two IShares holdings, EEM and IEMG. Dalio owned $1.54 billion and $885 million of each of these, respectively, accounting for 12.6% and 7.3% of the firm's positions.

After these four largest holdings, Dalio's positions become significantly smaller in terms of their share of total Bridgewater holdings. Nonetheless, the top 7 positions in the company portfolio account more more than three quarters of the total stock holdings.

Additionally, many of these top holdings are in ETFs, which sets Bridgewater apart from many of its competitor hedge funds, which also rely on significant management fees. (See also: Dalio: 'Bitcoin Is Not a Storehold of Wealth.')

Added PG&E, CVS and Celgene

Dalio made several purchases in the fourth quarter of 2017, but none was significant relative to the size of the largest holdings detailed above. The biggest purchase was for PG&E Corp. (PCG), but the total invested was only $38 million, accounting for just 0.3% of the full portfolio. Other stocks purchased include CVS Health Corp. (CVS), Cardinal Health, Inc. (CAH), and Celgene Corp. (CELG).

Bridgewater sold off $1.55 billion in EEM over the course of the fourth quarter. Its largest stock sale, by contrast, was Kroger Co. (KR), accounting for just $42.3 million, or 0.3%, of the full portfolio.

13Fs are useful as a means of determining how some of the most famous investors moved their money over the past quarter. However, by the time the information they contain is available to the public, it is long out of date and unlikely to be actionable for the everyday investor.