Budget constraint in Radner Sequential Trade Equilibria Suppose that $q$ is a k-tuple vector of prices for the k assets whose quantities are given by the k-tuple $\theta$. I have just read that in the Radner Sequential Trade Equilibrium (not sure if this goes by another name), where the trading of assets occurs in period t=0 (as opposed to t=1), the period-zero budget can be expressed as $q*\theta$, where $*$ denotes the inner product, and that this budget is non-positive. 

I feel like I must be misunderstanding something about this particular setting, because I have no idea how a budget could possibly be non-positive, as opposed to non-negative. 

Can someone give me some intuition for what's happening here?
In Radner's model each actor starts with an initial endowment, an asset vector $\omega$. You can trade this to any asset portfolio $x$ that has lower or equal value, so
$$x * q \leq \omega * q.$$
Denoting asset trades by $\theta = x - \omega$, you can also express this as
$$
\theta * q \leq 0.
$$