US STOCKS-Wall St up on Apple, Caterpillar; Ukraine weighs
* Indexes return to positive territory, but well off highs
* Apple rallies, announces 7-for-1 stock split
* Caterpillar gains after results; Verizon, 3M fall
* Indexes up: Dow 0.2 pct, S&P 0.4 pct, Nasdaq 0.7 pct (Updates to midday trading)
By Ryan Vlastelica
NEW YORK, April 24 (Reuters) - U.S. stocks rose in a volatile session on Thursday as Apple and Caterpillar were the latest high-profile names to post bullish results, though gains were limited by a resurgence of concerns related to Ukraine.
Markets had opened sharply higher, with the Nasdaq initially climbing more than 1 percent before turning negative in the first half-hour of trading. While Wall Street subsequently recovered, with gains again concentrated in the Nasdaq, it remained well off its early highs.
Much of the volatility was driven by Russian Defense Minister Sergei Shoigu, who said Russia started military drills near the border with Ukraine.
The issue "is a lit stick of dynamite" with remote chances of a peaceful resolution, said Todd Schoenberger, managing partner at LandColt Capital in New York. "All those geopolitical concerns warrant instability and higher commodity prices, and both of those are things Wall Street hates." Continuación...