Your observation that those two exhibit a strong negative correlation is correct. In a nutshell, this is because ABT goes up with the market, while VIIX goes down when the market is up. A more detailed reply:
Abbott Laboratories (ABT) discovers, develops, manufactures, and sells a broad and diversified line of health care products and services. It's a growth stock, which tends to outperform the market in a positive environment and lag the market in a negative environment.
VelocityShares VIX Short Term ETN (VIIX) is an exchange traded note, whose payout is linked to the payout of a long position in CBOE' Volatility Index Future. This instrument makes money when volatility in markets increases, which happens when markets go down. Such a vehicle tends to gain rapidly and suddenly when markets crash and slowly bleed money the rest of the time. Therefore it is suited rather to protect from losses on your other investments than as a stand-alone investment (unless you expect an imminent crash).
ABT and VIX Index are in deed strongly negatively correlated (I come up with approx. -0.8), which is a "design" feature of the VIX Index. The VIX would exhibit a negative correlation to virtually any "normal" stock and the overall market.