NEW YORK (Reuters) - Bridgewater Associates piled into six of the so-called Magnificent Seven megacap U.S. stocks in the first quarter, making an $800 million bet on Google-parent Alphabet while avoiding struggling shares of electric car-maker Tesla, securities filings showed.

The hedge fund founded by legendary investor Ray Dalio ended March with 5.4 million shares of Alphabet worth $810.3 million at the end of the first quarter, more than doubling its stake in the company since December. The stake was the fund's biggest single stock holding the end of the first quarter, according to the filings.

Shares in Alphabet are up roughly 23% this year, however, it is not possible to determine if Bridgewater still holds a position in the company or its size. The quarterly disclosures, known as 13-F filings, are made to the Securities and Exchange Commission around 45 days after the end of each quarter and may not reflect current positions.

Bridgewater's Big Tech shopping spree also saw the fund triple its stake in Microsoft to 579,525 shares in the first quarter, or $243.8 million. Shares of the company are up 12.5% year-to-date.

The hedge fund added over 1.8 million shares in Apple in the quarter, while also buying roughly one million shares in Amazon. Shares in Apple are down 1.3% and Amazon is up 21.6% year-to-date.

The firm, led by Nir Bar Dea, also increased its shares in Meta Platforms by 49%, to 994,051, or $482.7 million. Shares of the Facebook-parent are up 35.9% this year.

Chip giant Nvidia - whose shares are up 91.2% year-to-date - was another big Bridgewater bet in the quarter, as it almost tripled holdings in the company to 704,599 shares, or $636.6 million.

Big gains in the Magnificent Seven stocks - which have outsize weightings in the S&P 500 - have helped power markets higher this year and in 2023.

Absent from Bridgewater's portfolio were shares of Tesla, which have fallen almost 30% this year as the company faces fierce competition and slowing sales.

As a global macro hedge fund, Bridgewater places wagers on assets based on broader trends in sectors and geographies, not as a long/short stock picker.

Bridgewater also boosted its holdings of financial companies. Its stake in Citigroup rose by 23%, to 664,458, while also growing in Wells Fargo and Bank of New York Mellon.

(Reporting by Carolina Mandl, in New York, Editing by William Maclean)

By Carolina Mandl