This paper examines whether corporate alliance networks convey information about new investment opportunities. I hypothesize that firms located more centrally in their networks are exposed to greater information flows, which allows managers to rely less on their own stock prices as a source of information to make future investment decisions. Supporting this prediction, higher alliance network centrality leads to lower sensitivity of investment to stock prices. The impact is stronger for financially unconstrained firms, showing that financial constraints may limit firms’ ability to exploit their informational advantages from alliance networks. Additional tests exploiting quasi-exogenous changes in centrality due to indirect connections via alliance partners alleviate the endogeneity issue in alliance formation decision. The stock market reacts more positively to alliance announcements when new alliances are expected to provide greater informational benefits. Overall, my results show that alliance networks are conduits for value-enhancing information that affect corporate investment decision and valuation.