Investor Bill Ackman has added Visa, Mastercard, Netflix and three other new investments to his portfolios since his Pershing Square USA closed-end fund went public in late April.

The other new holdings are Intercontinental Exchange, Alcon, and S&P Global, according to a letter to shareholders of his investment management company, Pershing Square Inc. Ackman runs a concentrated portfolio of high-quality growth stocks that also include Meta Platforms, Amazon.com, and Microsoft.

The Pershing Square USA closed-end fund, which raised $5 billion in its initial public offering, has had disappointing performance so far. Closed-end funds issue a fixed number of shares and then can trade at a premium or discount from their portfolio value, or net asset value, based on investor demand.

The fund has gained 0.6% in net asset value, or NAV, through Aug. 11 relative to its IPO price of $50 a share on April 29, against a roughly 9% return for the S&P 500 over the same span.

The fund's price performance has been much worse, falling about 20% to $39.77, and trading at a roughly 20% discount to its net asset value. The fund shares were up 1.7% Thursday.

In a separate letter to holders of Pershing Square USA, Ackman vowed to address the discount, saying his firm would soon begin an "active marketing program for PSUS, which should assist us in narrowing the discount."

"We believe PSUS is an excellent long-term investment when purchased at NAV. We believe it represents an extraordinary bargain at the currently large discount to NAV at which it trades," he wrote.

Ackman attributed the big discount to a lack of marketing and "technical factors" from the IPO.

One problem for the fund is its high management fee of 2% annually, about double the fee on most U.S. closed-end funds and way above the 0.1% fee on many index funds and ETFs. Many closed-end funds repurchase shares if they trade at discounts to NAV or can face activist pressure to do so. Buybacks can help narrow a discount.

It's unlikely that Ackman will do so for the new closed-end fund, though, partly because buybacks reduce fee income to Pershing Square Inc., which he controls. The management company's shares rose 1.7% to $39.45 Thursday, after it reported its first quarterly results since going public in conjunction with the Pershing Square USA IPO.

Pershing Square Inc. is valued at about $16 billion, one of the richest valuation of any alternative investment managers relative to assets or profits. The firm had distributable earnings of 14 cents in the second quarter. The stock trades for about 70 times its annualized earnings in the period and 40 times next year's earnings.

Ackman's larger closed-end fund, the Europe-listed Pershing Square Holdings, is having one of its worst years relative to the S&P 500 since its inception in 2014. The fund was down 4.3% based on its NAV year to date through Aug. 11, against a roughly 14% return for the S&P 500. The fund's share price in the U.S. (ticker: PSHZF) is off about 18% to $52.

The fund now is behind the index over the past one and five years, but ahead over 10 years.

Ackman's performance has been hurt by declines in Meta Platforms and Howard Hughes, a holding in the European fund, so far this year. He has no exposure to the hot group of memory chip stocks like Micron.

Ackman's strategy is to buy what he views as great growth stocks with strong competitive advantages that can compound earnings and ride with them. The six new investments fit that bill.

Barron's has written favorably on the Ackman funds, arguing that investors who buy them at big discounts to NAV can get access to his investments and expertise at a cheap price.