PLURALITY OPINION
RICHARD H. EDELMAN, Justice.In this wrongful death and survival action, Jimmie Reinicke, individually and as legal representative of the Estates of Karen, Max, and Derrick Reinicke (collectively, “Reinicke”) appeals a judgment notwithstanding the verdict (“JNOV”) in favor of Aeroground, Inc. (“Aeroground”) on the grounds that the trial court erred in: (1) entering the JNOV because there was legally sufficient evidence to support the jury’s verdict; and (2) excluding from evidence (i) a post-accident drug test for marijuana and valium of Aeroground’s truck driver and (ii) the opinions of Texas Department of Public Safety (“DPS”) accident reconstructionists. We affirm.
Background
In this particularly tragic case, Rein-icke’s wife, Karen, and their two sons, Max and Derrick, were killed by a fire resulting from a highway traffic collision (the “accident”). Reinicke brought this wrongful death and survival action against Aero-ground (and others who are not parties to this appeal). At trial, the jury apportioned 50% of the negligence to Aeroground and awarded Reinicke damages totaling $23.25 million. However, the trial court ultimately concluded that there was no evidence that any negligence by Aeroground was a proximate cause of the accident, granted Aeroground’s motion for JNOV, and entered a take-nothing judgment.
JNOV
Reinicke’s first issue contends that the trial court erred in granting the JNOV because there was legally sufficient evidence that Aeroground’s negligence proximately caused the accident.
Standard of Review
A trial court may grant a JNOV if there is no evidence to support one or more of the jury findings on issues necessary to liability. Tiller v. McLure, 121 S.W.3d 709, 713 (Tex.2003). To determine whether there is no evidence to support a jury verdict (and thus uphold the JNOV), we view the evidence in a light that supports *387the challenged finding and disregard all evidence and inferences to the contrary. Id. If more than a scintilla of evidence supports the finding, the jury’s verdict must be upheld. Wal-Mart Stores, Inc. v. Miller, 102 S.W.3d 706, 709 (Tex.2003).
More than a scintilla of evidence exists when the evidence enables reasonable minds to differ in their conclusions. See Tarrant Reg’l Water Dist. v. Gragg, 151 S.W.3d 546, 552 (Tex.2004). Conversely, evidence that creates only a mere surmise or suspicion is no more than a scintilla and, thus, no evidence. Ford Motor Co. v. Ridgway, 135 S.W.3d 598, 601 (Tex.2004). Similarly, an inference that is stacked only upon other inferences, rather than direct evidence, is not legally sufficient evidence. See Marathon Corp. v. Pitzner, 106 S.W.3d 724, 728 (Tex.2003).
Overview of Negligence Grounds
In this case, an Aeroground 18-wheel tractor-trailer rig driven by Randy Peavy ran out of fuel while heading eastbound on Highway 290 and was parked on the shoulder, out of the lane of traffic. Peavy notified Aeroground, and it sent another driver, David Rodriguez, with another tractor with which to pull Peavy’s tractor away from the trailer and then pull the trailer to Aeroground’s yard. After the first tractor had been moved away from the trailer, but before the second tractor was connected to it, Karen’s van drifted off the roadway, collided with the rear corner of the parked trailer, went back onto the roadway, collided with both a Murco 18-wheel rig and the concrete wall dividing the highway, then caught on fire. Reinicke contends that the accident was caused by Aeroground’s negligence in the following respects: (1) Peavy allowed his rig to run out of fuel during rush hour on a busy highway, causing it to be placed in a dangerous position on the shoulder; (2) Peavy failed to put out emergency warning triangles to alert oncoming traffic that his rig was disabled and not moving; and (3) Rodriguez, an untrained driver who had a history of backing incidents, had backed the second tractor into the roadway in the path of Karen’s van immediately before the collision.
Negligence in Placing the Rig on the Shoulder
A person who creates a dangerous condition on premises, including a public highway, can be liable for injuries it causes even though he is not in formal control of the premises at the time of the injury.1 However, in this case, the charge submitted to the jury (the “charge”) contained only the elements pertaining to a negligent activity theory of recovery and not the additional elements required for a finding of liability under the independent theory of a defective condition of premises. See generally Comm, on PatteRN JüRY ChaRges, State BaR of Tex., Texas PatteRN Jury CHARGES — MALPRACTICE, PREMISES & PRODUCTS PJC 65.1 (2003).2 Therefore, the *388charge will support a recovery for an injury that was a contemporaneous result of an activity actually going on at the time of the injury, but not an injury resulting from a condition that was previously created by an activity.3
Reinicke’s first alleged ground of negligence, causing the trailer to be placed in a dangerous position along the highway, occurred while driving and parking the rig. That activity had ended when the tractor ran out of gas, well before the accident occurred. Therefore, to whatever extent Aeroground’s negligence in running out of gas and positioning the rig on the shoulder created a dangerous condition, the negligent activity charge submitted in this case will not support a finding of liability for common law negligence or premise liability for failing to: (1) exercise reasonable care in putting the trailer there; (2) warn of that condition; or (3) make it reasonably safe.4
Statutory Duty to Warn
Despite that a premise defect theory was not submitted to the jury, the charge would support liability for Reinicke’s second alleged ground of negligence, the failure to put out emergency warning triangles, because an independent duty to warn was imposed by statute, and the charge contained a negligence per se instruction that “the law requires the placement of emergency warning devices behind a disabled commercial motor vehicle within 10 minutes of becoming disabled.”5
*389A negligence per se theory requires a showing of proximate cause just as does an ordinary negligence theory. See Mo. Pac. R.R. Co. v. Am. Statesman, 552 S.W.2d 99, 103 (Tex.1977). In this case, the charge defined “proximate cause” as a cause that “produces an event, and without which ... [it] would not have occurred.” In this regard, the vital distinction is whether the negligent act: (1) set in motion a natural and unbroken chain of events that led directly to the injury;6 or (2) merely furnished a condition that made it possible for the injury to instead result from a separate act of negligence. IHS Cedars Treatment Ctr. v. Mason, 143 S.W.3d 794, 799 (Tex.2003). Similarly, if the evidence shows only a mere possibility that the plaintiffs injuries arose from the defendant’s negligence, or if it shows more than one equally probable cause, for any of which the defendant was not responsible, then the evidence is legally insufficient to support a finding of causation. See Hart v. Van Zandt, 399 S.W.2d 791, 792-93 (Tex.1965). Although a finding of cause-in-fact may be based on either direct or circumstantial evidence, it cannot be supported by mere conjecture, guess, or speculation. Marathon Corp. v. Pitzner, 106 S.W.3d 724, 727 (Tex.2003). Therefore, the causation evidence must show that the injury would not have occurred if the negligence had not occurred.7
In this case, it is undisputed that the rig was parked on the shoulder of the highway, out of the traveled lane of traffic, and that the accident occurred during daylight hours under dry weather conditions and clear visibility. Had Karen’s van remained in the roadway, as would ordinarily be expected of a driver in the exercise of reasonable care in such driving conditions, there is no evidence that any mishap would have occurred. Conversely, there is no evidence that the mere presence of the rig on the shoulder or the absence of warning triangles could have itself reasonably compelled a driver who was maintaining a safe distance, speed, lookout, and the like to leave the roadway. Nor is there any evidence that any movement of Karen’s van before, or while, drifting out of the lane of traffic toward the trailer on the shoulder was sudden or accompanied by any application of her brakes or abrupt steering change.8 Under these circumstances, the cause of the accident was whatever other event or condition caused the van to leave the roadway in the first place. Regardless whether that event or condition was an external factor or physical incapacity that was beyond Karen’s control, or some other occurrence that was within her control, there is no evidence that the presence of warning triangles would have changed its effect in any way, let alone prevented the accident. Therefore, although putting out emergency warning triangles would unquestionably have been better than not doing so, any conclusion that the accident would not have occurred if they had been used would be wholly speculative. There is thus no evidence that the failure to put out warning triangles was a cause of the *390accident.9
Backing the Second Tractor into the Roadway
Regarding Reinicke’s third alleged ground of negligence, backing the second tractor into the roadway in Karen’s path, it is undisputed that Rodriguez would have had to back his tractor up to the trailer to connect to it and that doing so would have required his tractor to move partway into the outside lane of traffic. However, there is no direct evidence that Rodriguez ever actually progressed to the point of backing his tractor into the roadway. Although the Murco truck driver, who was traveling ahead of Karen’s van, applied his brakes and moved to an inner lane as he approached the Aeroground rig, these actions would have been prudent just by reason of the rig being on the shoulder, and thus do not support an inference that there was a tractor in the roadway that precipitated them. Similarly, although there was evidence that Rodriguez was in a hurry to return the trailer to the Aero-ground yard, this fact is also not probative of whether he had actually backed his tractor onto the roadway when the accident occurred. As noted above, there is no evidence that any movement of Karen’s van before, or while, drifting out of the lane of traffic toward the trader on the shoulder was sudden or accompanied by any application of her brakes or abrupt steering change.
Because the evidence shows no more than a mere possibility that the accident could have been caused by Rodriguez backing his tractor into the roadway, and at least an equal probability that the van left the roadway for other possible reasons, any conclusion regarding causation can be reached only by speculation or stacking inferences. See Marathon, 106 S.W.3d at 729-30. Under these circumstances, there is no evidence that the accident was caused by Aeroground’s negligence, and Reinicke’s first issue is overruled.
Exclusion of Expert Opinion Testimony
Reinicke’s third issue challenges the trial court’s exclusion of the opinion testimony of two DPS accident reconstructionists, Manning and Davis, that Aeroground caused the wreck. Expert opinion testimony that is conclusory or speculative is legally insufficient to prove the stated conclusion. See Coastal Transp. Co. v. Crown Cent. Petroleum Corp., 136 S.W.3d 227, 232-33 (Tex.2004). Therefore, to constitute some evidence, an expert opinion must be supported by facts in evidence10 such that there is not too great an analytical gap between the data and the opinion offered. Kerr-McGee Corp. v. Helton, 133 S.W.3d 245, 254 (Tex.2004).
In this case, the facts that Manning and Davis relied upon included: (1) the respective locations of the various vehicles after the accident; (2) the location and length of skid marks from the Murco rig relative to the locations of the trailer and tractors, the calculated location at which Karen’s van collided with the Murco rig after hitting the trailer, and the points at which the van struck the concrete wall dividing the highway; and (3) various other matters occurring after the collision of Karen’s van *391with the trailer. However, we can find no portion of the record at which either expert explained how (iethe sequence of logical steps by which) a conclusion can be drawn from these facts regarding what caused Karen’s van to veer off the road in the first place. Nor is it apparent, without such an explanation, how any such conclusion logically follows from the body of data they relied upon. Under these circumstances, the expert opinions were coneluso-ry and/or speculative and would not have constituted evidence to support a finding that Aeroground’s negligence caused the accident. Therefore, Reinicke’s third issue is overruled.
Because Reinicke’s issues do not show any evidence to support the finding of causation against Aeroground, they fail to demonstrate error in granting the JNOV, and we need not address Aeroground’s cross-points. Accordingly, the judgment of the trial court is affirmed.
FOWLER, J., concurring.
SEYMORE, J., dissenting.
. City of Denton v. Page, 701 S.W.2d 831, 835 (Tex.1986); Strakos v. Gehring, 360 S.W.2d 787, 795-96 (Tex.1962) (recognizing that the law places upon a person who creates a dangerous condition on a public highway a duty to warn of the condition); see Lefmark Mgmt. Co. v. Old, 946 S.W.2d 52, 54 (Tex.1997); Sci. Spectrum, Inc. v. Martinez, 941 S.W.2d 910, 912 (Tex.1997).
. In addition to the ordinary negligence elements of failure to use ordinary/reasonable care, proximate cause, and damage, premise defect elements include: (1) the existence of a condition that posed an unreasonable risk of harm; and (2) actual or constructive knowledge of the condition by the defendant. See Keetch v. Kroger, 845 S.W.2d 262, 264 (Tex.1992). Because negligence and premise defect are independent theories of recovery, these additional elements cannot be deemed found where they have not been submitted in *388the jury charge. Clayton W. Williams, Jr., Inc. v. Olivo, 952 S.W.2d 523, 529 (Tex.1997).
. See Timberwalk Apartments, Partners, Inc. v. Cain, 972 S.W.2d 749, 753 (Tex.1998); Clayton W. Williams, 952 S.W.2d at 529; Keetch, 845 S.W.2d at 264.
. See Clayton W. Williams, 952 S.W.2d at 527, 529-30 (holding that a jury finding on negligent activity would not support a recovery for injury resulting from thread protectors left on the ground); Keetch, 845 S.W.2d at 264 (holding that a negligent activity theory would not support liability for a slippery condition previously created by spraying).
Based on the comment to Pattern Jury Charge instruction 65.2, the dissent contends that a negligent activity charge was sufficient to support liability against Aero-ground in this regard because the additional Corbin elements apply only as against a possessor, owner, or occupier of land. The dissent thereby infers from this PJC comment that a different and lesser standard of care applies to defendants who create dangerous conditions on property they do not own than applies to defendants who own or control the premises on which dangerous conditions exist.
This contention ignores the fundamental principle that negligence and premise defect are independent theories of recovery, rather than mere standards of care within a single theory that could differ among classes of defendants. In addition, it is refuted in that even a trespasser can be subject to liability for a condition he creates on land only if the Corbin elements are present, i.e., the condition poses an unreasonable risk of harm to others and the trespasser should recognize it as such. See Restatement (Second) of Torts § 381 (1965). Therefore, reading the comments to PJC 65.1 and 65.2 together, it is apparent that the PJC 65.2 instruction applies to the negligent activities of parties other than owners and occupiers who do not create the dangerous condition on the premises but whose concurrent negligent activity is also a cause of the injury for purposes of determining proportionate responsibility. However, as a practical matter, the lack of a premise defect submission in the charge had no actual effect on the outcome of the case because of the independent statutory duty to warn, discussed in the following section.
. Unlike a premise defect theory, a negligence per se theory considers whether there is an unexcused violation of a statute without regard to other considerations bearing on the reasonableness of the defendant's conduct, such as whether there is an unreasonably dangerous condition or the defendant’s awareness of it. See, e.g., Carter v. William Sommerville & Son, Inc., 584 S.W.2d 274, 278 (Tex.1979).
. See Hart v. Van Zandt, 399 S.W.2d 791, 793 (Tex.1965).
. See Excel Corp. v. Apodaca, 81 S.W.3d 817, 821-22 (Tex.2002) (holding evidence legally insufficient to prove that injury was caused by unsafe work practices where it failed to show that the injury would not have occurred if different practices had been followed); Southwest Key Program, Inc. v. Gil-Perez, 81 S.W.3d 269, 274-75 (Tex.2002) (holding evidence legally insufficient to prove that injury was caused by the lack of protective gear where it failed to show that injury would not have occurred if protective gear had been worn).
. Thus, contrary to the dissent, there is no evidence to support an inference that Karen was startled by a sudden perceived danger.
. Reinicke’s second issue challenges the exclusion of drug test evidence pertaining to Peavy's alleged negligence in creating the dangerous condition and/or failing to warn of it. Because of our conclusions that the charge does not support liability with regard to the condition, and there is no evidence of causation, we need not otherwise address the second issue.
. Marathon, 106 S.W.3d at 729.