Value or momentum!

Turns out both.

Found this paper by Clifford S. Asness, Tobias J. Moskowitz, and Lasse H. Pedersen1 (note: pdf link) via an article in the New York Times.

Here's the abstract:

We study jointly the returns to value and momentum strategies for individual stocks within countries, stock indices across countries, government bonds across countries, currencies, and commodities. Value and momentum generate abnormal returns everywhere we look. Exploring their common factor structure across asset classes, we find that value (momentum) in one asset class is positively correlated with value (momentum) in other asset classes, and value and momentum are negatively correlated within and across asset classes. Long-run consumption risk is positively linked to both value and momentum, as is global recession risk to a lesser extent, while global liquidity risk is related positively to value and negatively to momentum. These patterns emerge from the power of examining value and momentum everywhere at once and are not easily detectable when examining each asset class in isolation.