While Ark Investment Management chief Cathie Wood is generally a long-term investor, she frequently adds to or subtracts from her positions.

She usually buys into dips and sells into ascents. This week she snapped up a major tech stock.

The investment community has conflicting views toward Wood, who may be the country’s best-known investor after Warren Buffett. Admirers say she’s a technology visionary, while critics say she’s just a mediocre money manager.

Wood (Mama Cathie to her followers) soared to acclaim after a jaw-dropping return of 153% in 2020 and clearly-worded presentations of her investment strategy in frequent media appearances.

But her longer-term performance isn’t so stellar. Wood’s flagship Ark Innovation ETF ( ARKK ) , with $5.2 billion in assets, produced negative annualized returns of 8% for the past 12 months, 30% for three years and 1% for five years.

That’s desultory compared with the S&P 500. The index posted positive annualized returns of 21% for one year, 8% for three years, and 15% for five years. Ark Innovation’s numbers also fall well shy of Wood's goal for annual returns of at least 15% over five-year periods.

Cathie Wood’s straightforward strategy

Her investment philosophy is quite straightforward. Ark ETFs usually purchase emerging-company stocks in the high-tech categories of artificial intelligence, blockchain, DNA sequencing, energy storage, and robotics.

Wood maintains that companies in those categories will be game changers. Of course, these stocks are quite volatile, so the Ark funds’ values often fluctuate widely.

Investment research stalwart Morningstar is none too impressed with Wood and Ark Innovation ETF. Investing in young companies with slim earnings “demands forecasting talent, which ARK Investment Management lacks,” Morningstar analyst Robby Greengold wrote in March.

The potential of Wood’s five high-tech platforms listed above is “compelling,” he said. “But the firm’s ability to spot winners and manage their myriad risks is less so…. It has not proved it is worth the risks it takes.”

Related: Cathie Wood buys $59 million of pummeled tech stocks

This isn’t your father’s investment portfolio. “Results range from tremendous to horrendous” for Wood’s young, often unprofitable stocks, Greengold said.

Wood has defended herself from Morningstar’s criticism. “I do know there are companies like that one [Morningstar] that do not understand what we're doing,” she told Magnifi Media by Tifin in 2022.

“We do not fit into their style boxes. And I think style boxes will become a thing of the past, as technology blurs the lines between and among sectors.”

But some of Wood’s customers apparently agree with Morningstar. Over the past 12 months, Ark Innovation ETF suffered a net investment outflow of $2.3 billion, according to ETF research firm VettaFi. Ark Innovation’s asset total slid 13% in just the last 18 days.

Cathie Wood dives in for a mega-cap

On Monday, Wood purchased 14,686 shares of Google parent Alphabet ( GOOGL ) , valued at $2.4 million as of that day’s close.

The stock has dropped 14% from its July 10 record close of $193. So Wood may be picking up a bargain.

Related: Cathie Wood buys $28 million of battered tech stock

To be sure, Google shares are still up 26% over the past 12 months, so maybe it’s not the greatest bargain. (Yahoo Finance pegs Google's 12-month forward price-earnings multiple at 21.55.) In any case, Wood likes to have some blue-chip tech stocks as ballast for when her more speculative holdings drop.

Much of Alphabet’s recent slide came largely after its second-quarter earnings report. It showed that the company’s massive spending on artificial intelligence hasn’t yet paid off much in revenue or profit.

Grandiose AI expectations

Of course, it’s ridiculous to expect that the spending would pay off immediately. Al will take months, if not years, to generate substantial profits. And it may never do so in the way that some investors expect.

In any case, the pullback in AI hype hit the stocks of Alphabet and fellow megacap tech stocks in recent weeks.

Fund manager buys and sells:

As for the earnings data, Alphabet’s capital spending, including for AI, registered $13.2 billion in the second quarter, up 10% from a year earlier. That number exceeded analysts’ consensus forecast of $12.2 billion.

To be sure Alphabet’s revenue and profit beat analyst expectations. Revenue jumped 14% and profit surged 29%. So Wood certainly bought shares of a strong company.

The author owns shares of Alphabet.

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