Warren Buffett's little-known stock portfolio worth more than $5 billion nearly mirrored Berkshire Hathaway's trades last quarter. Here are its top holdings.

• Warren Buffett owns an under-the-radar stock portfolio worth more than $5 billion through Berkshire Hathaway.
• New England Asset Management portfolio is a subsidiary of General Re, which Berkshire bought for $22 billion in 1998.
• NEAM made strikingly similar trades to Buffett in the fourth quarter. These are its top 10 holdings.

Billionaire investor Warren Buffett owns an under-the-radar stock portfolio that made trades that were strikingly similar to the trades of Berkshire Hathaway last quarter.

Through Berkshire Hathaway, Buffett and his lieutenants manage a portfolio of stocks worth nearly $300 billion as of December 31.

And through General Re, which is a subsidiary of Berkshire Hathaway, Buffett owns a $5.4 billion stock portfolio that's managed by New England Asset Management, a firm that provides investment management services tailored to insurance companies.

New England Asset Management was acquired by General Re in 1995. In 1998, Berkshire Hathaway acquired General Re for $22 billion, making New England Asset Management a wholly owned subsidiary of Buffett's conglomerate.

While Buffett appears to have no influence over how the portfolio is managed by New England Asset Management, the portfolio does own similar stocks and made some trades that almost mirrored Berkshire Hathaway, according to 13F filings made with the SEC. 

New England Asset Management sold 90% of its US Bancorp position and 100% of its Bank of New York Mellon holding last quarter, while Berkshire Hathaway reduced its stake in US Bancorp by 91% and sold 59% of its stake in Bank of New York Mellon.

Other similarities between the two portfolios is that they're both extremely concentrated, with New England Asset Management's top 10 positions making up 91% of its portfolio. The top 10 holdings of Berkshire Hathaway's main stock portfolio make up 89% of its assets.

Additionally, New England Asset Management takes a long-term approach similar to Buffett and has a knack for owning some of its stocks for decades, like Chevron, Cisco, and JPMorgan, among others.

But there were some divergences between New England Asset Management and Berkshire Hathaway last quarter. For example, New England Asset Management's trimmed some of its stake in Apple, while Berkshire Hathaway bought more shares in the iPhone maker. 

These are the top 10 holdings of New England Asset Management. This list is as of December 31 and excludes ETF holdings and instead focuses on individual stocks. 

10. Cisco Systems

Ticker: CSCO
Market Value: $10.2 million
Percent of Portfolio: 0.19%
Change in Shares: -3,560 (-1%)

9. Lockheed Martin

Ticker: LMT
Market Value: $12.3 million
Percent of Portfolio: 0.23%
Change in Shares: +4,193 (+19%)

8. Microsoft

Ticker: MSFT
Market Value: $13.3 million
Percent of Portfolio: 0.24%
Change in Shares: -422 (0%)

7. JPMorgan

Ticker: JPM
Market Value: $14.1 million
Percent of Portfolio: 0.26%
Change in Shares: -1,649 (-1%)

6. Diageo

Ticker: DEO
Market Value: $40.6 million
Percent of Portfolio: 0.75%
Change in Shares: No change

5. US Bancorp

Ticker: USB
Market Value: $70.8 million
Percent of Portfolio: 1.30%
Change in Shares: -14,955,400 (-90%)

4. HP

Ticker: HPQ
Market Value: $442.7 million
Percent of Portfolio: 8.15%
Change in Shares: No change

3. Bank of America

Ticker: BAC
Market Value: $753.5 million
Percent of Portfolio: 13.88%
Change in Shares: No change

2. Chevron

Ticker: CVX
Market Value: $795.0 million
Percent of Portfolio: 14.64%
Change in Shares: -10,700 (0%)

1. Apple

Ticker: AAPL
Market Value: $2.66 billion
Percent of Portfolio: 48.92%
Change in Shares: -19,638 (0%)