Blackstone, Vanguard, and Wellington Management are launching an interval fund that will invest in public equities, bonds and private markets, as part of their effort to expand private-market offerings to retail clients. The firms have laid out plans for an interval fund, through which investors will be able to make quarterly withdrawals capped between 5% and a quarter of the fund’s net-asset value. The trio partnered up earlier this year, amid a rising trend of ventures between firms that typically manage public stocks and bonds and those that invest in alternatives. Wellington will manage the interval fund — the first from the partnership — and draw its investments from all three firms. It will allocate up to 60% in public equities, up to 30% in fixed income and as much as 40% in private markets investments, according to the filing, which did not disclose what fees clients will be charged. Traditional asset managers have been seeking ways to move beyond stock and bond funds into higher-margin businesses, including private equity and private credit. At the same time, alternative asset firms have been searching for ways to tap a bigger slice of the retail market. Many have resorted to interval funds which can offer exposure to assets ranging from real estate to direct lending for buyouts.