By Chris Isidore, CNN Business

(CNN) -- No Model S or Model X cars on the Tesla assembly line is apparently no problem for investors.

Friday Tesla revealed it did not build any of its two most expensive models, the Model S sedan and Model X SUV, in the first quarter. But it achieved a record number of deliveries of the less expensive Model 3 sedan and Model Y SUV in the same period.

Markets were closed Friday, but Tesla stock opened above $700 in trading Monday, reaching a high of $708, before retreating to just below $700 by midday, still up 5% from Thursday's close.

Tesla did not explain why it did not build any of the more expensive models in the quarter. It said it is ramping up production of the new versions of the Model S and Model Y, but in January CEO Elon Musk had promised that Tesla would resume deliveries of the new version of the Model S in February, and the new version of the Model X soon thereafter. Most automakers don't shut down production of models that are being updated for three months.

Some analysts believe suspending Model S and X production was due to the computer chip shortage that has hurt automakers around the world and caused widespread shutdowns of factories and assembly lines.

The high point for Tesla shares Monday was enough to briefly take the stock out of bear market territory. Tesla has been down more than 20% from its record high close of $883.09, which it hit the day before releasing fourth quarter results that were below Wall Street forecasts.

The fact that Tesla was able build 180,338 of its less expensive models, up from 179,757 cars built in the fourth quarter, was a notable accomplishment, said Dan Ives, tech analyst for Wedbush Securities, who upgraded his recommendation on Tesla shares over the weekend.

"In our opinion the first quarter delivery numbers released on Friday was a paradigm changer and shows that the pent-up demand globally for Tesla's Model 3/Y is hitting its next stage of growth as part of a global green tidal wave underway," Ives wrote. "We now believe Tesla could exceed 850,000 deliveries for the year with 900,000 a stretch goal."

Morgan Stanley auto analyst Adam Jonas said he still expects the chip shortage to cause Tesla to report a modest drop in second quarter sales, despite its ability to significantly top first quarter forecasts. But he said the strong report leaves the company in good shape to reach the consensus forecast of 842,000 cars sold this year, up from nearly 500,000 cars in 2020.

But some critics of the company believe the report actually shows trouble ahead for Tesla.

"The only thing that matters for Tesla in the first quarter of 2021, and going forward, in our view, is sequential growth... because this is what's important for growth companies," wrote Gordon Johnson of GLJ Research.

He said growing delivery volume just 2% quarter-over-quarter "is not a good thing."

Johnson also said profit could be hurt because Tesla probably made about $20,000 in operating profit on each of the more expensive Model S and Model X, and only $4,000 on each Model 3 and Model Y.

"So why is the first quarter 2021 delivery number a positive?" he wrote. "Why is everyone gushing over these numbers?"