Stocks finished the month of April breaking to new highs, with the S&P 500 rising above 1597. But May Day selling put a temporary hold on the bullish celebration that will certainly occur if the S&P 500 can make a clean break above psychological resistance at 1600. Was May Day the start of the usual “Sell in May and go away” practice?

Despite an environment of uninspiring economic reports, stocks have regained their footing once again. Last week, bulls found that they simply couldn’t ignore the Boston bombing like all the other worrisome news, but the quick capture of the perpetrators has removed the domestic terrorism cloud.

Market timing is tough duty. Even as stocks have risen inexorably and we all knew it couldn’t go up in a straight line, still picking tops is hard. You can be wrong for a long time, and either lose your shirt shorting the market, or miss out on big gains by staying out.

Bulls have regained their footing and recruited some reinforcements, as the S&P 500 on Wednesday powered right through its 5.5-year intraday high of 1576 on increased trading volume to set a new record of 1589.

Last week, I talked about the impressive strength this year in the Dow Jones Transportation Average, but it since has been hit by investors’ renewed worries about global economic growth and financial stability. Its fall has been led by weakness in the airlines.

The Dow Jones Transportation Index is up an impressive +16.7% year-to-date through Wednesday, as it runs interference for the broader Dow Industrials (up +10.8%) and tries to prod the bulls ahead.

Well, you gotta hand it to the bears; they are pulling out all stops in their effort to derail the bull train, just as the S&P 500 tries to eclipse its all-time high. This time they trotted out the tiny republic of Cyprus (pop. 1.1 million) and its battle with the EU over the terms of its financial bailout. Steal a big chunk of depositors’ accounts?

I was watching the ABC World News the other evening, and I was struck by the commercials they ran. The target demographic is obviously an older crowd (and since I was watching, I guess that includes me). Advertised products within the short 30-minute newscast addressed a variety of age-related ailments like low-T, erectile dysfunction, overactive bladder, constipation, hemorrhoids, and loose dentures.

Cash flush investors who have been waiting for a buying opportunity must be feeling like the guy standing outside the sold-out concert looking for someone willing to sell him a ticket. Stocks just won’t pull back much, despite a huge wall of worry that one might expect would put some quicksand under the bulls’ feet.

For most of 2013 thus far, the market has been on a steady rise without volatility within a narrow channel. Bulls have been looking to recruit reinforcements for their assault on the all-time highs on the S&P 500 large caps and Dow Jones blue chips, after already taking out the all-time highs on the Russell 2000 small caps and S&P 400 mid caps.