Near-term S&P 500 indicators are "inflecting positively from an oversold condition," suggesting stocks should be bought now ahead of the "next leg" of the equities market advance, Oppenheimer analysts said in a note.

Oppenheimer said it found September has historically posted marginally positive returns when the S&P 500 starts the month above its 200-day moving average. Although this month's returns in an uptrend are still below the all-period average, Oppenheimer advised that stocks should be bought now.

Recent strength in the S&P 500 suggests the bull market is resuming after the August pullback, and Oppenheimer expects "new highs above 2,490 resistance over the coming weeks." Analysts added that the S&P 500 will continue to outperform the Europe Stoxx 600 "despite valuation differentials that favor the contrary."

Oppenheimer also said a near-term correction of the "overbought Euro/oversold dollar" could leave West Texas Intermediate crude oil prices "vulnerable" to the downside because of dollar weakness in a "bearish response to what is typically a bullish catalyst." If the breakout for the euro and the weakness for the dollar reverse, weak commodities will get weaker, analysts wrote.

Analysts also made a case for investing in technology stocks. The tech-heavy Nasdaq is rated as a buy and poised to "lead equities higher over the coming quarters based on its steadily rising trend and resiliency in an environment of slight to moderate economic growth," Oppenheimer wrote. Analysts suggested investors maintain at least 25% of their portfolio as technology holdings.

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