The Nasdaq-100 PowerShares QQQ (NasdaqGM: QQQ) is outperforming the broader market in August as the ETF benefits from the latest breakout in Apple (NasdaqGS: AAPL) shares.

For the month ended Aug. 17, QQQ was up 7.5% compared with a 4.3% gain for iShares S&P 500 (NYSEArca: IVV).

Apple is the largest stock in the Nasdaq-100 ETF at 19.2% of the portfolio.

Shares of tech giant gained 2% on Monday to nearly $665 and were up 60.7% year to date heading into the session, according to Morningstar.

Also Monday, Apple became the most valuable stock to have ever traded, CNBC reports.

Shares of the iPhone and iPad producer have continued to rally in the wake of disappointing quarterly results. Apple has a market cap of more than $600 billion.

“In fact, Apple has seen its market cap double from $300 billion to $600 billion in a mere 19 months,” CNBC reported.

With Monday’s gain, Apple eclipsed Microsoft’s peak market cap hit over 12 years ago in late 1999. “That happened at the height of the dot-com boom and just three months before the Nasdaq Composite peaked,” according to the report.

PowerShares QQQ

Full disclosure: Tom Lydon’s clients own AAPL and QQQ.