Cathie Wood got back on track last year. The CEO and stock picker of Ark Invest's aggressive growth exchange-traded funds (ETFs) trounced the market in 2023 after fading awfully in back-to-back years.

She publishes the daily transactions across her ETFs, so what's she buying these days? Wood added to her existing positions in Tesla (TSLA -1.11%), Ark 21Shares Bitcoin ETF (ARKB -1.61%), and Cerus (CERS 0.59%) on Thursday. Let's look at a closer look at the stocks she is buying.

Tesla

Wood doesn't hesitate in adding to some of her positions when they fall out of favor, and that was the case on Thursday for Tesla. Shares of the leading maker of electric cars shifted into reverse for a 12% drop after the company posted disappointing financial results. Wood took advantage of the sale to add to her top holdings.

Tesla posted an adjusted profit of $0.71 a share on $25.2 billion in revenue for the holiday quarter, falling short of analyst estimates on both ends of the income statement. Revenue growth has decelerated sharply in four of the past five quarters, including the less than 4% year-over-year increase in its latest report.

A person sits in a car with their head resting on their hand.

Image source: Getty Images.

Tesla has been lowering prices on its cars since late 2022 in its two largest markets. The cuts have been necessary to expand its reach and hit production targets, but margins understandably contracted in 2023. Tesla is bracing investors to expect "notably lower" vehicle volume growth in 2024, but it sees healthy growth potential for its energy storage business. It's a lull before the next major rollout of a next-gen compact vehicle expected next year.

The automaker remains the undisputed leader in this growing market, but the stock's historically lofty valuation is tricky to justify when growth stalls. It was Wood's largest holding just a couple of months ago, but the stock's slide -- down nearly 40% since its summertime peak -- finds it now clocking in as her fourth largest position.

Ark 21Shares Bitcoin ETF

Wood is a vocal fan of crypto, and she isn't afraid to eat her own cooking. Ark launched its own Bitcoin fund two weeks ago, when stateside regulators finally cleared the way for spot Bitcoin exchange-traded funds to hit the market. She bought some shares on Thursday.

Ark 21Shares Bitcoin ETF offers investors a way to play one of last year's hottest markets, as the leading decentralized currency more than doubled in 2023. The fund provides direct exposure to Bitcoin that is kept in cold storage by an institutional-grade custodian, promising greater protection than individual investors turning to traditional custody options.

The ETF projects a reasonable expense ratio of 0.21%, but it's currently waiving those fees as a way to stand out in a suddenly crowded market. It's one of the larger players among the 11 funds that launched this month with $529 million worth of Bitcoin as its one and only asset.

Cerus

Blood was spilled at Cerus last year. The biotech stock working on blood safety ended its streak of six straight years of revenue growth at 17% or better. A run of 23 consecutive quarters of year-over-year growth ended in the first quarter of 2023, and preliminary results for all of last year suggest flat if not declining results.

Things should get better for the company behind the Intercept platform that reduces pathogen loads in different blood components. In issuing its preliminary fourth-quarter numbers earlier this month, it also initiated guidance calling for 10% to 12% in product revenue growth in 2024. The stock has been cut in half since the start of last year, but Wood is a believer. Revenue growth turned positive in the second half of last year, and momentum is building heading into the new year.