As of Monday, shops in Europe and the US accounting for 34% of its selling space have been reopened, reaching 79% on June 15.
The FTSE 100 conglomerate said first sales were “encouraging”, with queues outside shops and larger basket sizes, however this trading pattern may not continue in the long term.
Like-for-like sales were lower than the same period last year.
At the start of reopenings the fast-fashion chain had £1.5bn of stock on hand and had commitments for another £400mln, compared to a typical stockholding level of £900mln.
Some summer items will be held in storage to sell next year.
Closures between March and May brought to monthly losses of £650mln as previously announced, while overheads in April and May were cut by 50%.
"Primark’s higher dependence on continuity lines and decisions to store part of the Spring Summer stock for next year will help it avoid unnecessary markdowns," analysts at Liberum commented.
"Risks remain over the next few months as higher markdowns across the industry could force Primark to revisit the markdown strategy, but we see a likely economic downturn across Europe to increase demand for the market-leading priced products offered by Primark."
Shares shot up 6% to 1,929.11p on Monday in early trades, then rose by 8% to 1,970.8p at noon.