While Warren Buffett’s portfolio is known for its reliability, no investor is infallible. This brief look at three of his holdings reveals why two are likely to remain strong options, and why one may not be living up to its billing.

Eventide Asset Management LLC expanded its investment in Monolithic Power Systems, Inc. by a modest 0.1% during the first quarter. After purchasing 24 additional shares, the firm now holds a total of 42,231 shares, worth roughly $24.49 million.